No project diagnostic fixes

src/VisualStudio/Core/Def/Implementation/TableDataSource/AbstractTableEntriesSnapshot.cs

@@ -184,6 +184,11 @@ protected string GetFileName(string original, string mapped)
 
         protected string GetProjectName(Workspace workspace, ProjectId projectId)
         {
+            if (projectId == null)
+            {
+                return null;
+            }
+
             var project = workspace.CurrentSolution.GetProject(projectId);
             if (project == null)
             {
@@ -195,6 +200,11 @@ protected string GetProjectName(Workspace workspace, ProjectId projectId)
 
         protected IVsHierarchy GetHierarchy(Workspace workspace, ProjectId projectId)
         {
+            if (projectId == null)
+            {
+                return null;
+            }
+
             var vsWorkspace = workspace as VisualStudioWorkspace;
             if (vsWorkspace == null)
             {

src/VisualStudio/Core/Def/Implementation/TaskList/HostDiagnosticUpdateSource.cs

@@ -13,6 +13,7 @@
 namespace Microsoft.VisualStudio.LanguageServices.Implementation.TaskList
 {
     [Export(typeof(IDiagnosticUpdateSource))]
+    [Export(typeof(AbstractHostDiagnosticUpdateSource))]
     [Export(typeof(HostDiagnosticUpdateSource))]
     internal sealed class HostDiagnosticUpdateSource : AbstractHostDiagnosticUpdateSource
     {