Do not close application when reporting CGNS reading failure

When opening a file that is assumed to be a valid CGNS file, a first Parse is done. If the file is invalid, it leads to an unexpected closing of the application. (see #18680 (closed)) The patch now report the issue and do not clean up the CGNS library and do not call the exiting feature. Thus the application will not crash but it could be possible that the CGNS library can not open any new file.