check for non-zero exit in mapper.py

[ptrebert]

Hi, may I suggest that you change this line

https://github.com/ablab/VerityMap/blob/8d241f4750b71ee87669f41b3c976c4cbbb2be1d/veritymap/py_src/mapper.py#L42

to subprocess.check_call or to explicitly check the returncode attribute? In the current form, errors occurring in the subprocess will go unnoticed.

Best, Peter

[seryrzu]

Thank you for the suggestion! Addressed in https://github.com/ablab/VerityMap/pull/21