No error reported when JSON object is merged with JSON array

As part of Inline type name handling, the type name is merged with the object data. In this case, however, we attempt to merge the type name (which is guaranteed to be a JSON object) with the previously created JSON array. This is not allowed and results in an error, which is not passed through.

The fix is to always return errors to the caller.

Originally posted by @logmanoriginal in #27