Trap errors in functions that are not native perl functions (like
acos() and csc(), etc.). In the past, if an error occurred within the
definition of a function, the error message that was reported was the
internal error within the definition of the function. For example
csc(0) would report "illegal division by zero", while acos(-2) would
report "can't take sqrt of -3". Now the errors will be "can't take
csc of 0" and "can't take acos of -2".