Fix crash when accessing base_exception error_context

When accessing the base_exception error_context or error_info, a crash is possible when working with views. When building the ViewErrorContext a PyObject* is incorrectly DECREF'd which causes can lead to the crash.

NOTE: Earlier thought on believing PyDict_Copy only did a shallow copy was incorrect. PyDict_Copy will increment all the keys and values in the dict object when copying to a new dict object correctly. See CPython code.