As is obvious from the code, PyModule_GetDict() can fail if being passed a non-module object, and when the (unlikely) dict creation at the end fails. The documentation of the C-API function should be fixed to reflect that, i.e. it should state that NULL is returned in the case of an error.

PyObject *
PyModule_GetDict(PyObject *m)
{
    PyObject *d;
    if (!PyModule_Check(m)) {
        PyErr_BadInternalCall();
        return NULL;
    }
    d = ((PyModuleObject *)m) -> md_dict;
    if (d == NULL)
        ((PyModuleObject *)m) -> md_dict = d = PyDict_New();
    return d;
}