1 files changed, 4 insertions, 5 deletions
diff --git a/src/new_fields/Doc.ts b/src/new_fields/Doc.ts
index 7f7263cf1..c2cfda079 100644
--- a/src/new_fields/Doc.ts
+++ b/src/new_fields/Doc.ts
@@ -186,7 +186,8 @@ export namespace Doc {
     }
 
     // compare whether documents or their protos match
-    export function AreProtosEqual(doc: Doc, other: Doc) {
+    export function AreProtosEqual(doc?: Doc, other?: Doc) {
+        if (!doc || !other) return false;
         let r = (doc === other);
         let r2 = (doc.proto === other);
         let r3 = (other.proto === doc);
@@ -211,13 +212,11 @@ export namespace Doc {
         return Array.from(results);
     }
 
-
     export function MakeAlias(doc: Doc) {
-        const alias = new Doc;
         if (!GetT(doc, "isPrototype", "boolean", true)) {
-            alias.proto = doc.proto;
+            return Doc.MakeCopy(doc);
         }
-        return alias;
+        return new Doc;
     }
 
     export function MakeCopy(doc: Doc, copyProto: boolean = false): Doc {