Fix merge conflict

src/Workspaces/Core/Portable/Diagnostics/Extensions.cs

@@ -179,7 +179,7 @@ private static string GetAssemblyQualifiedName(Type type)
                     var filterSpan = documentAnalysisScope.Span;
                     var kind = documentAnalysisScope.Kind;
 
-                    ImmutableDictionary<DiagnosticAnalyzer, ImmutableArray<Diagnostic>> diagnosticsByAnalyzerMap;
+                    ImmutableDictionary<DiagnosticAnalyzer, ImmutableArray<Diagnostic>>? diagnosticsByAnalyzerMap;
                     switch (kind)
                     {
                         case AnalysisKind.Syntax:

src/Workspaces/SharedUtilitiesAndExtensions/Workspace/Core/Extensions/ISolutionExtensions.cs

@@ -65,16 +65,5 @@ public static TextDocument GetRequiredTextDocument(this Solution solution, Docum
 
             return document;
         }
-
-        public static TextDocument GetRequiredTextDocument(this Solution solution, DocumentId documentId)
-        {
-            var document = solution.GetTextDocument(documentId);
-            if (document == null)
-            {
-                throw new InvalidOperationException(WorkspaceExtensionsResources.The_solution_does_not_contain_the_specified_document);
-            }
-
-            return document;
-        }
     }
 }