The code generated for the Py_UNICODE converter (and derived converter LPCWSTR) looks like:

const Py_UNICODE *name; ... if (!_PyArg_ParseXXX(..., name, ...)) { goto exit; } ... exit: PyMem_Free((void *)name);

If parsing fails, PyMem_Free() is called for uninitialized variable.

It is the only converter with non-trivial cleanup which does not have a mandatory initializer.