Currently, they support throwing exceptions if unit tests are running. It would be great for any code to be able to say, "I want exceptions thrown" instead, either by defining a constant or setting something temporarily in $CFG, eg:

1.
define('CONVERTERRORSTOEXCEPTIONS', 1);
// whatever code that might call error or print_error

2.
$CFG->converterrorstoexceptions = true;
// whatever code that might call error or print_error
$CFG->converterrorstoexcetions = false;

3.
$tmpsetting = $CFG->converterrorstoexceptions;
$CFG->converterrorstoexceptions = true;
// whatever code that might call error or print_error
$CFG->converterrorstoexceptions = $tmpsetting;

I prefer 3.