Rename type for clarity

src/EditorFeatures/Core/Implementation/Diagnostics/AbstractDiagnosticsTaggerProvider.cs

@@ -152,14 +152,14 @@ private void ProduceTags(TaggerContext<TTag> context, DocumentSnapshotSpan spanT
             var suppressedDiagnosticsSpans = (NormalizedSnapshotSpanCollection?)null;
             buffer?.Properties.TryGetProperty(PredefinedPreviewTaggerKeys.SuppressDiagnosticsSpansKey, out suppressedDiagnosticsSpans);
 
-            var eventArgs = _diagnosticService.GetDiagnosticsUpdatedEventArgs(
+            var buckets = _diagnosticService.GetDiagnosticBuckets(
                 workspace, document.Project.Id, document.Id, context.CancellationToken);
 
-            foreach (var updateArg in eventArgs)
+            foreach (var bucket in buckets)
             {
                 ProduceTags(
                     context, spanToTag, workspace, document,
-                    suppressedDiagnosticsSpans, updateArg, cancellationToken);
+                    suppressedDiagnosticsSpans, bucket, cancellationToken);
             }
         }
 
@@ -167,13 +167,13 @@ private void ProduceTags(TaggerContext<TTag> context, DocumentSnapshotSpan spanT
             TaggerContext<TTag> context, DocumentSnapshotSpan spanToTag,
             Workspace workspace, Document document,
             NormalizedSnapshotSpanCollection? suppressedDiagnosticsSpans,
-            UpdatedEventArgs updateArgs, CancellationToken cancellationToken)
+            DiagnosticBucket bucket, CancellationToken cancellationToken)
         {
             try
             {
-                var id = updateArgs.Id;
+                var id = bucket.Id;
                 var diagnostics = _diagnosticService.GetDiagnostics(
-                    workspace, document.Project.Id, document.Id, id, false, cancellationToken);
+                    workspace, document.Project.Id, document.Id, id, includeSuppressedDiagnostics: false, cancellationToken);
 
                 var isLiveUpdate = id is ISupportLiveUpdate;
 

src/EditorFeatures/Test/Diagnostics/MockDiagnosticService.cs

@@ -34,7 +34,7 @@ public MockDiagnosticService()
         {
         }
 
-        public ImmutableArray<DiagnosticData> GetDiagnostics(Workspace workspace, ProjectId projectId, DocumentId documentId, object id, bool includeSuppressedDiagnostics, CancellationToken cancellationToken)
+        public ImmutableArray<DiagnosticData> GetDiagnostics(Workspace workspace, ProjectId? projectId, DocumentId? documentId, object? id, bool includeSuppressedDiagnostics, CancellationToken cancellationToken)
         {
             Assert.Equal(projectId, GetProjectId(workspace));
             Assert.Equal(documentId, GetDocumentId(workspace));
@@ -42,14 +42,14 @@ public ImmutableArray<DiagnosticData> GetDiagnostics(Workspace workspace, Projec
             return _diagnostic == null ? ImmutableArray<DiagnosticData>.Empty : ImmutableArray.Create(_diagnostic);
         }
 
-        public ImmutableArray<UpdatedEventArgs> GetDiagnosticsUpdatedEventArgs(Workspace workspace, ProjectId projectId, DocumentId documentId, CancellationToken cancellationToken)
+        public ImmutableArray<DiagnosticBucket> GetDiagnosticBuckets(Workspace workspace, ProjectId? projectId, DocumentId? documentId, CancellationToken cancellationToken)
         {
             Assert.Equal(projectId, GetProjectId(workspace));
             Assert.Equal(documentId, GetDocumentId(workspace));
 
             return _diagnostic == null
-                ? ImmutableArray<UpdatedEventArgs>.Empty
-                : ImmutableArray.Create(new UpdatedEventArgs(this, workspace, GetProjectId(workspace), GetDocumentId(workspace)));
+                ? ImmutableArray<DiagnosticBucket>.Empty
+                : ImmutableArray.Create(new DiagnosticBucket(this, workspace, GetProjectId(workspace), GetDocumentId(workspace)));
         }
 
         internal void CreateDiagnosticAndFireEvents(Workspace workspace, Location location)

src/EditorFeatures/TestUtilities/LanguageServer/AbstractLanguageServerProtocolTests.cs

@@ -171,7 +171,7 @@ protected static string ApplyTextEdits(LSP.TextEdit[] edits, SourceText original
             return text.ToString();
         }
 
-        protected static LSP.SymbolInformation CreateSymbolInformation(LSP.SymbolKind kind, string name, LSP.Location location, string? containerName = null)
+        protected static LSP.SymbolInformation CreateSymbolInformation(LSP.SymbolKind kind, string name, LSP.Location location, string containerName = "")
             => new LSP.SymbolInformation()
             {
                 Kind = kind,
@@ -223,7 +223,8 @@ protected static LSP.CompletionParams CreateCompletionParams(LSP.Location caret,
             string text, LSP.CompletionItemKind kind, string[] tags,
             LSP.CompletionParams requestParameters, bool preselect = false,
             string[]? commitCharacters = null)
-            => new LSP.VSCompletionItem()
+        {
+            var item = new LSP.VSCompletionItem()
             {
                 FilterText = text,
                 InsertText = text,
@@ -237,11 +238,18 @@ protected static LSP.CompletionParams CreateCompletionParams(LSP.Location caret,
                     TextDocument = requestParameters.TextDocument,
                     Position = requestParameters.Position
                 },
-                Icon = tags != null ? new ImageElement(tags.ToImmutableArray().GetFirstGlyph().GetImageId()) : null,
                 Preselect = preselect,
-                CommitCharacters = commitCharacters
             };
 
+            if (tags != null)
+                item.Icon = new ImageElement(tags.ToImmutableArray().GetFirstGlyph().GetImageId());
+
+            if (commitCharacters != null)
+                item.CommitCharacters = commitCharacters;
+
+            return item;
+        }
+
         private protected static CodeActionResolveData CreateCodeActionResolveData(string uniqueIdentifier, LSP.Location location)
             => new CodeActionResolveData(uniqueIdentifier, location.Range, CreateTextDocumentIdentifier(location.Uri));
 

src/Features/Core/Portable/Diagnostics/DiagnosticBucket.cs

+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+#nullable enable
+
+namespace Microsoft.CodeAnalysis.Diagnostics
+{
+    internal readonly struct DiagnosticBucket
+    {
+        /// <summary>
+        /// The identity of update group. 
+        /// </summary>
+        public readonly object Id;
+
+        /// <summary>
+        /// <see cref="Workspace"/> this update is associated with.
+        /// </summary>
+        public readonly Workspace Workspace;
+
+        /// <summary>
+        /// <see cref="ProjectId"/> this update is associated with, or <see langword="null"/>.
+        /// </summary>
+        public readonly ProjectId? ProjectId;
+
+        /// <summary>
+        /// <see cref="DocumentId"/> this update is associated with, or <see langword="null"/>.
+        /// </summary>
+        public readonly DocumentId? DocumentId;
+
+        public DiagnosticBucket(object id, Workspace workspace, ProjectId? projectId, DocumentId? documentId)
+        {
+            Id = id;
+            Workspace = workspace;
+            ProjectId = projectId;
+            DocumentId = documentId;
+        }
+    }
+}

src/Features/Core/Portable/Diagnostics/DiagnosticService.cs

@@ -262,11 +262,11 @@ private ImmutableArray<DiagnosticData> GetSpecificDiagnostics(Workspace workspac
                 buffer.Clear();
                 if (source.SupportGetDiagnostics)
                 {
-                    result.AddRange(source.GetDiagnostics(workspace, projectId, documentId, null, includeSuppressedDiagnostics, cancellationToken));
+                    result.AddRange(source.GetDiagnostics(workspace, projectId, documentId, id: null, includeSuppressedDiagnostics, cancellationToken));
                 }
                 else
                 {
-                    AppendMatchingData(source, workspace, projectId, documentId, null, buffer);
+                    AppendMatchingData(source, workspace, projectId, documentId, id: null, buffer);
 
                     foreach (var data in buffer)
                     {
@@ -283,10 +283,10 @@ private ImmutableArray<DiagnosticData> GetSpecificDiagnostics(Workspace workspac
             return result.ToImmutable();
         }
 
-        public ImmutableArray<UpdatedEventArgs> GetDiagnosticsUpdatedEventArgs(
+        public ImmutableArray<DiagnosticBucket> GetDiagnosticBuckets(
             Workspace workspace, ProjectId projectId, DocumentId documentId, CancellationToken cancellationToken)
         {
-            using var _1 = ArrayBuilder<UpdatedEventArgs>.GetInstance(out var result);
+            using var _1 = ArrayBuilder<DiagnosticBucket>.GetInstance(out var result);
             using var _2 = ArrayBuilder<Data>.GetInstance(out var buffer);
 
             foreach (var source in _updateSources)
@@ -296,7 +296,7 @@ private ImmutableArray<DiagnosticData> GetSpecificDiagnostics(Workspace workspac
 
                 AppendMatchingData(source, workspace, projectId, documentId, id: null, buffer);
                 foreach (var data in buffer)
-                    result.AddRange(new UpdatedEventArgs(data.Id, data.Workspace, data.ProjectId, data.DocumentId));
+                    result.AddRange(new DiagnosticBucket(data.Id, data.Workspace, data.ProjectId, data.DocumentId));
             }
 
             return result.ToImmutable();

src/Features/Core/Portable/Diagnostics/IDiagnosticService.cs

@@ -2,11 +2,11 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
+#nullable enable
+
 using System;
-using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Threading;
-using Microsoft.CodeAnalysis.Common;
 
 namespace Microsoft.CodeAnalysis.Diagnostics
 {
@@ -26,11 +26,12 @@ internal interface IDiagnosticService
         /// <summary>
         /// Get current diagnostics stored in IDiagnosticUpdateSource
         /// </summary>
-        ImmutableArray<DiagnosticData> GetDiagnostics(Workspace workspace, ProjectId projectId, DocumentId documentId, object id, bool includeSuppressedDiagnostics, CancellationToken cancellationToken);
+        ImmutableArray<DiagnosticData> GetDiagnostics(Workspace workspace, ProjectId? projectId, DocumentId? documentId, object? id, bool includeSuppressedDiagnostics, CancellationToken cancellationToken);
 
         /// <summary>
-        /// Get current UpdatedEventArgs stored in IDiagnosticUpdateSource
+        /// Get current buckets stored our diagnostics are grouped into.  Specific buckets can be retrieved by calling
+        /// <see cref="IDiagnosticServiceExtensions.GetDiagnostics(IDiagnosticService, DiagnosticBucket, bool, CancellationToken)"/>.
         /// </summary>
-        ImmutableArray<UpdatedEventArgs> GetDiagnosticsUpdatedEventArgs(Workspace workspace, ProjectId projectId, DocumentId documentId, CancellationToken cancellationToken);
+        ImmutableArray<DiagnosticBucket> GetDiagnosticBuckets(Workspace workspace, ProjectId? projectId, DocumentId? documentId, CancellationToken cancellationToken);
     }
 }

src/Features/Core/Portable/Diagnostics/IDiagnosticServiceExtensions.cs

+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Immutable;
+using System.Threading;
+using Microsoft.CodeAnalysis.PooledObjects;
+using Roslyn.Utilities;
+
+namespace Microsoft.CodeAnalysis.Diagnostics
+{
+    internal static class IDiagnosticServiceExtensions
+    {
+        public static ImmutableArray<DiagnosticData> GetDiagnostics(this IDiagnosticService service, DiagnosticBucket bucket, bool includeSuppressedDiagnostics, CancellationToken cancellationToken)
+            => service.GetDiagnostics(bucket.Workspace, bucket.ProjectId, bucket.DocumentId, bucket.Id, includeSuppressedDiagnostics, cancellationToken);
+
+        public static ImmutableArray<DiagnosticData> GetDiagnostics(this IDiagnosticService service, Document document, bool includeSuppressedDiagnostics, CancellationToken cancellationToken)
+        {
+            var project = document.Project;
+            var workspace = project.Solution.Workspace;
+
+            using var _ = ArrayBuilder<DiagnosticData>.GetInstance(out var result);
+
+            foreach (var bucket in service.GetDiagnosticBuckets(workspace, project.Id, document.Id, cancellationToken))
+            {
+                Contract.ThrowIfFalse(workspace.Equals(bucket.Workspace));
+                Contract.ThrowIfFalse(document.Id.Equals(bucket.DocumentId));
+
+                var diagnostics = service.GetDiagnostics(bucket, includeSuppressedDiagnostics, cancellationToken);
+                result.AddRange(diagnostics);
+            }
+
+            return result.ToImmutable();
+        }
+    }
+}

src/Features/LanguageServer/Protocol/CustomProtocol/FindUsagesLSPContext.cs

@@ -177,17 +177,17 @@ public override async ValueTask OnReferenceFoundAsync(SourceReferenceItem refere
             var result = new LSP.VSReferenceItem
             {
                 ContainingMember = properties.TryGetValue(
-                    AbstractReferenceFinder.ContainingMemberInfoPropertyName, out var referenceContainingMember) ? referenceContainingMember : null,
+                    AbstractReferenceFinder.ContainingMemberInfoPropertyName, out var referenceContainingMember) ? referenceContainingMember : "",
                 ContainingType = properties.TryGetValue(
-                    AbstractReferenceFinder.ContainingTypeInfoPropertyName, out var referenceContainingType) ? referenceContainingType : null,
+                    AbstractReferenceFinder.ContainingTypeInfoPropertyName, out var referenceContainingType) ? referenceContainingType : "",
                 DefinitionId = definitionId,
                 DefinitionText = definitionText,    // Only definitions should have a non-null DefinitionText
                 DisplayPath = location.Uri.LocalPath,
-                DocumentName = documentSpan == default ? null : documentSpan.Document.Name,
+                DocumentName = documentSpan == default ? "" : documentSpan.Document.Name,
                 Id = id,
                 Kind = symbolUsageInfo.HasValue ? ProtocolConversions.SymbolUsageInfoToReferenceKinds(symbolUsageInfo.Value) : Array.Empty<ReferenceKind>(),
                 Location = location,
-                ProjectName = documentSpan == default ? null : documentSpan.Document.Project.Name,
+                ProjectName = documentSpan == default ? "" : documentSpan.Document.Project.Name,
                 ResolutionStatus = ResolutionStatusKind.ConfirmedAsReference,
                 Text = text,
             };

src/Features/LanguageServer/Protocol/Extensions/ProtocolConversions.cs

@@ -105,7 +105,7 @@ public static LSP.TextEdit TextChangeToTextEdit(TextChange textChange, SourceTex
         {
             return new LSP.TextEdit
             {
-                NewText = textChange.NewText,
+                NewText = textChange.NewText ?? "",
                 Range = TextSpanToRange(textChange.Span, text)
             };
         }

src/Features/LanguageServer/Protocol/Handler/Initialize/InitializeHandler.cs

@@ -59,6 +59,7 @@ public Task<LSP.InitializeResult> HandleRequestAsync(LSP.InitializeParams reques
                     ReferencesProvider = true,
                     ProjectContextProvider = true,
                     ExecuteCommandProvider = new LSP.ExecuteCommandOptions(),
+                    SupportsDiagnosticRequests = true,
                     TextDocumentSync = new LSP.TextDocumentSyncOptions
                     {
                         Change = LSP.TextDocumentSyncKind.None

src/Features/LanguageServer/Protocol/Handler/Symbols/WorkspaceSymbolsHandler.cs

@@ -13,6 +13,7 @@
 using Microsoft.CodeAnalysis.Host.Mef;
 using Microsoft.CodeAnalysis.NavigateTo;
 using Microsoft.VisualStudio.LanguageServer.Protocol;
+using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.LanguageServer.Handler
 {
@@ -30,7 +31,8 @@ public override async Task<SymbolInformation[]> HandleRequestAsync(WorkspaceSymb
         {
             var solution = SolutionProvider.GetCurrentSolutionForMainWorkspace();
             var searchTasks = Task.WhenAll(solution.Projects.Select(project => SearchProjectAsync(project, request, cancellationToken)));
-            return (await searchTasks.ConfigureAwait(false)).SelectMany(s => s).ToArray();
+            var result = await searchTasks.ConfigureAwait(false);
+            return result.SelectMany(a => a).ToArray();
 
             // local functions
             static async Task<ImmutableArray<SymbolInformation>> SearchProjectAsync(Project project, WorkspaceSymbolParams request, CancellationToken cancellationToken)
@@ -46,19 +48,25 @@ static async Task<ImmutableArray<SymbolInformation>> SearchProjectAsync(Project
                         request.Query,
                         searchService.KindsProvided,
                         cancellationToken).ConfigureAwait(false);
+
                     var projectSymbolsTasks = Task.WhenAll(items.Select(item => CreateSymbolInformation(item, cancellationToken)));
-                    return (await projectSymbolsTasks.ConfigureAwait(false)).ToImmutableArray();
+                    var result = await projectSymbolsTasks.ConfigureAwait(false);
+                    return result.WhereNotNull().ToImmutableArray();
                 }
 
                 return ImmutableArray.Create<SymbolInformation>();
 
-                static async Task<SymbolInformation> CreateSymbolInformation(INavigateToSearchResult result, CancellationToken cancellationToken)
+                static async Task<SymbolInformation?> CreateSymbolInformation(INavigateToSearchResult result, CancellationToken cancellationToken)
                 {
+                    var location = await ProtocolConversions.TextSpanToLocationAsync(result.NavigableItem.Document, result.NavigableItem.SourceSpan, cancellationToken).ConfigureAwait(false);
+                    if (location == null)
+                        return null;
+
                     return new SymbolInformation
                     {
                         Name = result.Name,
                         Kind = ProtocolConversions.NavigateToKindToSymbolKind(result.Kind),
-                        Location = await ProtocolConversions.TextSpanToLocationAsync(result.NavigableItem.Document, result.NavigableItem.SourceSpan, cancellationToken).ConfigureAwait(false),
+                        Location = location,
                     };
                 }
             }

src/VisualStudio/Core/Def/Implementation/LanguageClient/InProcLanguageServer.cs

@@ -426,7 +426,7 @@ static LanguageServer.Protocol.Diagnostic ConvertToLspDiagnostic(DiagnosticData
         private bool IncludeDiagnostic(DiagnosticData diagnostic) =>
             diagnostic.Properties.GetOrDefault(nameof(DocumentPropertiesService.DiagnosticsLspClientName)) == _clientName;
 
-        private static LanguageServer.Protocol.Range? GetDiagnosticRange(DiagnosticDataLocation? diagnosticDataLocation, SourceText text)
+        private static LanguageServer.Protocol.Range GetDiagnosticRange(DiagnosticDataLocation? diagnosticDataLocation, SourceText text)
         {
             var linePositionSpan = DiagnosticData.GetLinePositionSpan(diagnosticDataLocation, text, useMapped: true);
             return ProtocolConversions.LinePositionToRange(linePositionSpan);

src/VisualStudio/Core/Def/Implementation/TableDataSource/VisualStudioBaseDiagnosticListTable.LiveTableDataSource.cs

@@ -166,9 +166,9 @@ private object CreateAggregationKey(object data)
 
             private void PopulateInitialData(Workspace workspace, IDiagnosticService diagnosticService)
             {
-                foreach (var args in diagnosticService.GetDiagnosticsUpdatedEventArgs(workspace, projectId: null, documentId: null, cancellationToken: CancellationToken.None))
+                foreach (var bucket in diagnosticService.GetDiagnosticBuckets(workspace, projectId: null, documentId: null, cancellationToken: CancellationToken.None))
                 {
-                    OnDataAddedOrChanged(args);
+                    OnDataAddedOrChanged(bucket);
                 }
             }
 

src/VisualStudio/Core/Test/Diagnostics/DiagnosticTableDataSourceTests.vb

@@ -841,16 +841,16 @@ Namespace Microsoft.VisualStudio.LanguageServices.UnitTests.Diagnostics
                 Return diagnostics
             End Function
 
-            Public Function GetDiagnosticsArgs(workspace As Workspace, projectId As ProjectId, documentId As DocumentId, cancellationToken As CancellationToken) As ImmutableArray(Of UpdatedEventArgs) Implements IDiagnosticService.GetDiagnosticsUpdatedEventArgs
+            Public Function GetDiagnosticsArgs(workspace As Workspace, projectId As ProjectId, documentId As DocumentId, cancellationToken As CancellationToken) As ImmutableArray(Of DiagnosticBucket) Implements IDiagnosticService.GetDiagnosticBuckets
                 Assert.NotNull(workspace)
 
-                Dim diagnosticsArgs As ImmutableArray(Of UpdatedEventArgs)
+                Dim diagnosticsArgs As ImmutableArray(Of DiagnosticBucket)
 
                 If documentId IsNot Nothing Then
                     diagnosticsArgs = Items.Where(Function(t) t.DocumentId Is documentId) _
                                            .Select(
                                                 Function(t)
-                                                    Return New UpdatedEventArgs(
+                                                    Return New DiagnosticBucket(
                                                         New ErrorId(Me, If(CObj(t.DocumentId), t.ProjectId)),
                                                         workspace, t.ProjectId, t.DocumentId)
                                                 End Function).ToImmutableArrayOrEmpty()
@@ -858,14 +858,14 @@ Namespace Microsoft.VisualStudio.LanguageServices.UnitTests.Diagnostics
                     diagnosticsArgs = Items.Where(Function(t) t.ProjectId Is projectId) _
                                            .Select(
                                                 Function(t)
-                                                    Return New UpdatedEventArgs(
+                                                    Return New DiagnosticBucket(
                                                         New ErrorId(Me, If(CObj(t.DocumentId), t.ProjectId)),
                                                         workspace, t.ProjectId, t.DocumentId)
                                                 End Function).ToImmutableArrayOrEmpty()
                 Else
                     diagnosticsArgs = Items.Select(
                                                 Function(t)
-                                                    Return New UpdatedEventArgs(
+                                                    Return New DiagnosticBucket(
                                                         New ErrorId(Me, If(CObj(t.DocumentId), t.ProjectId)),
                                                         workspace, t.ProjectId, t.DocumentId)
                                                 End Function).ToImmutableArrayOrEmpty()

src/VisualStudio/Xaml/Impl/Implementation/LanguageServer/Handler/Completion/CompletionHandler.cs

@@ -56,24 +56,12 @@ public override async Task<CompletionItem[]> HandleRequestAsync(CompletionParams
 
         private static CompletionItem CreateCompletionItem(XamlCompletionItem xamlCompletion, DocumentId documentId, SourceText text, Position position)
         {
-            TextEdit? textEdit = null;
-
-            if (xamlCompletion.Span.HasValue)
-            {
-                textEdit = new TextEdit
-                {
-                    NewText = xamlCompletion.InsertText,
-                    Range = ProtocolConversions.LinePositionToRange(text.Lines.GetLinePositionSpan(xamlCompletion.Span.Value))
-                };
-            }
-
-            return new VSCompletionItem
+            var item = new VSCompletionItem
             {
                 Label = xamlCompletion.DisplayText,
                 CommitCharacters = xamlCompletion.CommitCharacters,
                 Detail = xamlCompletion.Detail,
                 InsertText = xamlCompletion.InsertText,
-                TextEdit = textEdit,
                 Preselect = xamlCompletion.Preselect,
                 SortText = xamlCompletion.SortText,
                 FilterText = xamlCompletion.FilterText,
@@ -82,9 +70,20 @@ private static CompletionItem CreateCompletionItem(XamlCompletionItem xamlComple
                 Icon = xamlCompletion.Icon,
                 Data = new CompletionResolveData { ProjectGuid = documentId.ProjectId.Id, DocumentGuid = documentId.Id, Position = position, DisplayText = xamlCompletion.DisplayText }
             };
+
+            if (xamlCompletion.Span.HasValue)
+            {
+                item.TextEdit = new TextEdit
+                {
+                    NewText = xamlCompletion.InsertText,
+                    Range = ProtocolConversions.LinePositionToRange(text.Lines.GetLinePositionSpan(xamlCompletion.Span.Value))
+                };
+            }
+
+            return item;
         }
 
-        private static CompletionItem[] CreateErrorItem(string message, string? details = null)
+        private static CompletionItem[] CreateErrorItem(string message, string details = "")
         {
             var item = new CompletionItem
             {

src/VisualStudio/Xaml/Impl/Implementation/LanguageServer/Handler/OnAutoInsert/OnAutoInsertHandler.cs

@@ -53,12 +53,12 @@ public override async Task<LSP.DocumentOnAutoInsertResponseItem[]> HandleRequest
                 return response.ToArray();
             }
 
-            var insertText = result.TextChange.NewText;
+            var insertText = result.TextChange.NewText ?? "";
             var insertFormat = LSP.InsertTextFormat.Plaintext;
             if (result.CaretOffset.HasValue)
             {
                 insertFormat = LSP.InsertTextFormat.Snippet;
-                insertText = insertText?.Insert(result.CaretOffset.Value, "$0");
+                insertText = insertText.Insert(result.CaretOffset.Value, "$0");
             }
 
             response.Add(new LSP.DocumentOnAutoInsertResponseItem

src/Workspaces/CoreTestUtilities/Remote/InProcRemostHostClient.cs

@@ -372,8 +372,10 @@ public override int WriteTimeout
 
                 public override Task CopyToAsync(Stream destination, int bufferSize, CancellationToken cancellationToken) => _stream.CopyToAsync(destination, bufferSize, cancellationToken);
 
+#pragma warning disable CS0672 // Member overrides obsolete member
                 public override object InitializeLifetimeService()
                     => throw new NotSupportedException();
+#pragma warning restore CS0672 // Member overrides obsolete member
 
 #if !NETCOREAPP
                 public override ObjRef CreateObjRef(Type requestedType)