Null values in lists

[johnthepink]

Lists from GraphQL should all be of the same type, in theory. But, It may also return a null in the middle of a list:

      nestedArray: [
        {
          stringField: 'This is a string too!',
          numberField: 6,
          nullField: null,
        },
        {
          stringField: 'This is a string also!',
          numberField: 7,
          nullField: null,
        },
        null,
      ],

Currently, this will error out:

 Error: Can't find field stringField on result object abcd.nestedArray.2.

[johnthepink]

Closed via #70