rl_env.step() exits the program if illegal move is passed instead of throwing an exception

[carlbalmer]

If an illegal move is supplied to rl_env.step() the underlying c library just exits with a message to stderr:

Input requirements failed at ../../../hanabi_learning_environment/hanabi_lib/hanabi_state.cc:222 in ApplyMove: MoveIsLegal(move)
Aborted (core dumped)

It would be nice if rl_env.step() would raise a ValueError instead.

[carlbalmer]

Tried to throw an exception in hanabi_state.cc ApplyMove() but cffi does not seem to pass exceptions from c++ to python.