Fix broken state with errors null

CHANGELOG.md

@@ -9,6 +9,7 @@ Expect active development and potentially significant breaking changes in the `0
 - Fix bug where there could be store inconsistencies for two dependent optimistic updates [PR #1144](https://github.com/apollostack/apollo-client/pull/1144)
 - Allow optional mutation arguments. [PR #1174](https://github.com/apollostack/apollo-client/pull/1174)
 - Fix typings error with `strictNullChecks` [PR #1188](https://github.com/apollostack/apollo-client/pull/1188)
+- Gracefully handle `null` GraphQL errors. [PR #1208](https://github.com/apollostack/apollo-client/pull/1208)
 - Allow optional mutation arguments. [PR #1174](https://github.com/apollostack/apollo-client/pull/1174)
 
 ### 0.7.3

src/errors/ApolloError.ts

@@ -16,7 +16,8 @@ import { GraphQLError } from 'graphql';
     // If we have GraphQL errors present, add that to the error message.
     if (Array.isArray(err.graphQLErrors) && err.graphQLErrors.length !== 0) {
       err.graphQLErrors.forEach((graphQLError: GraphQLError) => {
-        message += 'GraphQL error: ' + graphQLError.message + '\n';
+        const errorMessage = graphQLError ? graphQLError.message : 'Error message not found.';
+        message += `GraphQL error: ${errorMessage}\n`;
       });
     }
 

test/QueryManager.ts

@@ -414,6 +414,36 @@ describe('QueryManager', () => {
     });
   });
 
+  // Easy to get into this state if you write an incorrect `formatError`
+  // function with graphql-server or express-graphql
+  it('error array with nulls (handle non-spec-compliant server) #1185', (done) => {
+    assertWithObserver({
+      done,
+      query: gql`
+      query people {
+        allPeople(first: 1) {
+          people {
+            name
+          }
+        }
+      }`,
+      result: {
+        errors: [null],
+      },
+      observer: {
+        next() {
+          done(new Error('Should not fire next for an error'));
+        },
+        error(error) {
+          assert.deepEqual((error as any).graphQLErrors, [null]);
+          assert.equal(error.message, 'GraphQL error: Error message not found.');
+          done();
+        },
+      },
+    });
+  });
+
+
   it('handles network errors', (done) => {
     assertWithObserver({
       done,