Comment 3 for bug 1799132

In general, the error means that you attempted to index an object that doesn't have that functionality. You are trying to subscript an object which you think is a list or dict, but actually is None. NoneType is the type of the None object which represents a lack of value, for example, a function that does not explicitly return a value will return None. 'NoneType' object is not subscriptable is the one thrown by python when you use the square bracket notation object[key] where an object doesn't define the __getitem__ method . e.g.: http://net-informations.com/python/err/nonetype.htm