Use more descriptive exception in c_library.py
Use more descriptive exception in c_library.py

mrh1997/pyclibrary,duguxy/pyclibrary,mrh1997/pyclibrary,duguxy/pyclibrary,MatthieuDartiailh/pyclibrary,MatthieuDartiailh/pyclibrary,duguxy/pyclibrary,mrh1997/pyclibrary