Merge pull request #21835 from pselden/mobx-apollo-data

[mobx-apollo] data in the query result can potentially be undefined

types/mobx-apollo/index.d.ts

@@ -19,7 +19,7 @@ export interface MobxApolloQueryOptions<T> extends WatchQueryOptions {
 
 export interface MobxApolloQuery<T> {
     loading: boolean;
-    data: T;
+    data?: T;
     error?: ApolloError;
     ref: ObservableQuery<T>;
 }

types/mobx-apollo/mobx-apollo-tests.ts

@@ -27,7 +27,7 @@ class PostStore {
     }
 
     get posts() {
-        return this.postsQuery.data.posts;
+        return this.postsQuery.data && this.postsQuery.data.posts;
     }
 }