Unwrap targetinvocationexxceptions.

src/EditorFeatures/TestUtilities/Workspaces/TestWorkspace.cs

@@ -191,9 +191,14 @@ protected override void Dispose(bool finalize)
         private static IList<Exception> Flatten(ICollection<Exception> exceptions)
         {
             var aggregate = new AggregateException(exceptions);
-            return aggregate.Flatten().InnerExceptions;
+            return aggregate.Flatten().InnerExceptions
+                .Select(UnwrapException)
+                .ToList();
         }
 
+        private static Exception UnwrapException(Exception ex)
+            => ex is TargetInvocationException targetEx ? (targetEx.InnerException ?? targetEx) : ex;
+
         internal void AddTestSolution(TestHostSolution solution)
         {
             this.OnSolutionAdded(SolutionInfo.Create(solution.Id, solution.Version, solution.FilePath, projects: solution.Projects.Select(p => p.ToProjectInfo())));