Use IVsSolution to get the correct IVsProject for an IVsHierarchy

Fixes crashes associated with InvisibleEditor

src/VisualStudio/Core/Def/Implementation/ProjectSystem/InvisibleEditor.cs

@@ -42,7 +42,7 @@ public InvisibleEditor(IServiceProvider serviceProvider, string filePath, IVisua
             _needsSave = needsSave;
 
             var invisibleEditorManager = (IIntPtrReturningVsInvisibleEditorManager)serviceProvider.GetService(typeof(SVsInvisibleEditorManager));
-            var vsProject = projectOpt?.Hierarchy as IVsProject;
+            var vsProject = TryGetProjectOfHierarchy(projectOpt?.Hierarchy);
             var invisibleEditorPtr = IntPtr.Zero;
             Marshal.ThrowExceptionForHR(invisibleEditorManager.RegisterInvisibleEditor(filePath, vsProject, 0, null, out invisibleEditorPtr));
 
@@ -84,6 +84,34 @@ public InvisibleEditor(IServiceProvider serviceProvider, string filePath, IVisua
             }
         }
 
+        private IVsProject TryGetProjectOfHierarchy(IVsHierarchy hierarchyOpt)
+        {
+            // The invisible editor manager will fail in cases where the IVsProject passed to it is not consistent with
+            // the IVsProject known to IVsSolution (e.g. if the object is a wrapper like AbstractHostObject created by
+            // the CPS-based project system). This method returns an IVsProject instance known to the solution, or null
+            // if the project could not be determined.
+            if (hierarchyOpt == null)
+            {
+                return null;
+            }
+
+            if (!ErrorHandler.Succeeded(hierarchyOpt.GetGuidProperty(
+                (uint)VSConstants.VSITEMID.Root,
+                (int)__VSHPROPID.VSHPROPID_ProjectIDGuid,
+                out var projectId)))
+            {
+                return null;
+            }
+
+            var solution = (IVsSolution)_serviceProvider.GetService(typeof(SVsSolution));
+            if (!ErrorHandler.Succeeded(solution.GetProjectOfGuid(projectId, out var projectHierarchy)))
+            {
+                return null;
+            }
+
+            return projectHierarchy as IVsProject;
+        }
+
         public IVsTextLines VsTextLines
         {
             get