Add fetchMoreForQueryId safeguards

packages/apollo-client/CHANGELOG.md

@@ -6,11 +6,15 @@
   (Android), by instead setting the `prototype` of `this` manually.
   [Issue #3236](https://github.com/apollographql/apollo-client/issues/3236)
   [PR #3306](https://github.com/apollographql/apollo-client/pull/3306)
-- Added safeguards to make sure `QueryStore.initQuery` and
+- Added safeguards to make sure `QueryStore.initQuery` and   
   `QueryStore.markQueryResult` don't try to set the network status of a
-  `fetchMoreForQueryId` query, if it does not exist in the store.
+  `fetchMoreForQueryId` query, if it does not exist in the store. This was
+  happening when a query component was unmounted while a `fetchMore` was still
+  in flight.
   [Issue #3345](https://github.com/apollographql/apollo-client/issues/3345)
+  [Issue #3466](https://github.com/apollographql/apollo-client/issues/3466)
   [PR #3367](https://github.com/apollographql/apollo-client/pull/3367)
+  [PR #3469](https://github.com/apollographql/apollo-client/pull/3469)
 
 ### 2.3.0
 - fixed edge case bug of changing fetchPolicies right after resetStore with no variables present

packages/apollo-client/src/data/__tests__/queries.ts

@@ -72,4 +72,25 @@ describe('QueryStore', () => {
       },
     );
   });
+
+  describe('markQueryError', () => {
+    it(
+      'should set the network status of a `fetchMoreForQueryId` query to ' +
+        '`ready` in the store, if it exists',
+      () => {
+        queryStore.markQueryError(queryId, null, queryId);
+        expect(queryStore.get(queryId).networkStatus).toBe(NetworkStatus.ready);
+      },
+    );
+
+    it(
+      'should not attempt to set the network status of a ' +
+        '`fetchMoreForQueryId` query, if it does not exist in the store',
+      () => {
+        expect(() => {
+          queryStore.markQueryError(queryId, null, 'id-does-not-exist');
+        }).not.toThrow("Cannot set property 'networkStatus' of undefined");
+      },
+    );
+  });
 });