Change the order of checks in applyRemoteEvent()

Author: schmidt-sebastian

packages/firestore/src/local/local_store.ts

@@ -516,21 +516,32 @@ export class LocalStore {
           documentBuffer.getEntries(txn, updatedKeys).next(existingDocs => {
             remoteEvent.documentUpdates.forEach((key, doc) => {
               const existingDoc = existingDocs.get(key);
+
+              // Note: The order of the steps below is important, since we want
+              // to ensure that rejected limbo resolutions (which fabricate
+              //  NoDocuments with SnapshotVersion.NONE) never add documents to
+              // cache.
               if (
-                existingDoc == null ||
-                doc.version.compareTo(existingDoc.version) > 0 ||
-                (doc.version.compareTo(existingDoc.version) === 0 &&
-                  existingDoc.hasPendingWrites)
+                doc instanceof NoDocument &&
+                doc.version.isEqual(SnapshotVersion.MIN)
               ) {
+                // NoDocuments with SnapshotVersion.MIN are used in manufactured
+                // events. We remove these documents from cache since we lost
+                // access.
                 documentBuffer.addEntry(doc);
                 changedDocs = changedDocs.insert(key, doc);
               } else if (
-                doc instanceof NoDocument &&
-                doc.version.isEqual(SnapshotVersion.MIN)
+                existingDoc == null ||
+                doc.version.compareTo(existingDoc.version) > 0 ||
+                (doc.version.compareTo(existingDoc.version) === 0 &&
+                  existingDoc.hasPendingWrites)
               ) {
-                // NoDocuments with SnapshotVersion.MIN are used in manufactured events (e.g. in the
-                // case of a limbo document resolution failing). We remove these documents from cache
-                // since we lost access.
+                // TODO(index-free): Comment in this assert when we enable
+                // Index-Free queries
+                assert(
+                  !SnapshotVersion.MIN.isEqual(remoteEvent.snapshotVersion),
+                  'Cannot add a document when the remote version is zero'
+                );
                 documentBuffer.removeEntry(key);
                 changedDocs = changedDocs.insert(key, doc);
               } else {