Be resilient to null-paths/names for Documents/Projects in SqlitePersistence layer.

src/Workspaces/Core/Desktop/Workspace/SQLite/SQLitePersistentStorage_BulkPopulateIds.cs

@@ -202,6 +202,11 @@ string GetDocumentIdString(Document document)
 
             void AddIfUnknownId(string value, HashSet<string> stringsToAdd)
             {
+                if (value == null)
+                {
+                    return;
+                }
+
                 if (!_stringToIdMap.TryGetValue(value, out var id))
                 {
                     stringsToAdd.Add(value);

src/Workspaces/Core/Desktop/Workspace/SQLite/SQLitePersistentStorage_StringIds.cs

@@ -34,6 +34,11 @@ private void FetchStringTable(SqlConnection connection)
 
         private int? TryGetStringId(SqlConnection connection, string value)
         {
+            if (value == null)
+            {
+                return null;
+            }
+
             // First see if we've cached the ID for this value locally.  If so, just return
             // what we already have.
             if (_stringToIdMap.TryGetValue(value, out int existingId))