Fix newData raising error per #3455 issue

[pawelkleczek]

This PR attempts to fix issue #3455 by splittting destructuring result after newData is retrieved:

-    const { result, error, delay, newData } = response;
+    const { newData } = response;

     if (newData) {
       response.result = newData();
       this.mockedResponsesByKey[key].push(response);
     }

+    const { result, error, delay } = response;
+
     if (!result && !error) {
       throw new Error(
         `Mocked response should contain either result or error: ${key}`

[apollo-cla]

@pawelkleczek: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Meteor Contributor Agreement here: https://contribute.meteor.com/

[hwillson]

Thanks @pawelkleczek!