High-performance 32- and 64-bit global-state (thread-unsafe) and thread-safe uniform pseudorandom number generators for C, C++ and Python. Provided as an installable package.
The two arguments are parsed as int long, but upon converting to int32_t, they are the same number. Which means it runs mt19937_uint(0, NULL), which leads to division by zero.
Solution: cast the results of PyArg_ParseTuple and check their values. It is okay if, for instance, mt19937_span32(10, 10) crashes. C code is unsafe for performance reasons. But Python should provide a safety net.