TypeError coming from mixins.py

[nathan-gilbert]

Hi,

I'm seeing a TypeError being emitted from this library occasionally. Specifically at

File "<omitted>/quickbooks/mixins.py", line 333, in query
     if object_name in json_data["QueryResponse"]:                                                                                                                                                                                                                                                
                       ~~~~~~~~~^^^^^^^^^^^^^^^^^                                                                                                                                                                                                                          
     TypeError: 'NoneType' object is not subscriptable   

It looks like qb.query(select) can return None (maybe when no results are returned? Maybe API error?) This causes TypeError to be thrown outside of the library itself because of trying access a property on a None object.