fix: verify that query.latestResult is not null

Author: tauu

packages/graphql/lib/src/core/query_manager.dart

@@ -493,7 +493,7 @@ class QueryManager {
     ObservableQuery<Object?> query,
     Map<String, dynamic>? cachedData,
   ) =>
-      cachedData != null &&
+      cachedData != null && query.latestResult != null &&
       (alwaysRebroadcast || !_deepEquals(query.latestResult!.data, cachedData));
 
   void setQuery(ObservableQuery<Object?> observableQuery) {