Athena-aware could use =cerr= before throwing an exception, but all
Athena-aware classes should use =MSG::FATAL= and/or throw an exception.
When using =MsgStream=, note that a call to e.g. =msg() << MSG::VERBOSE= that is suppressed by the output level has a higher runtime cost than
a call suppressed by =if (msgLvl <= MSG::VERBOSE)=. The =ATH_MSG= macros (=ATH_MSG_INFO= and =ATH_MSG_DEBUG= etc) wrap =msg()= calls in appropriate if statements and
are preferred in general for two reasons: they take up less space in the source code and indicate immediately that the message is correctly handled.
- *Check for all errors reported from functions.* [<<check-return-status>>]
