When a goal throws an exception during initialization (-g flag), the
system now asserts g_caused_exception(Goal, Exception) in the user
module. This allows custom toplevels (-t flag) to check if an error
occurred and handle it appropriately.
Example usage:
scryer-prolog -g "throw(error)" -t check_error
Where check_error can be:
:- dynamic(g_caused_exception/2).
check_error :-
( g_caused_exception(_, E) ->
write('Error: '), write(E), nl, halt(1)
; halt(0)
).
This enables scripts to use custom toplevels for sophisticated error
handling and exit code logic.
Addresses: https://github.com/mthom/scryer-prolog/pull/3147#issuecomment-3503875719
Co-Authored-By: J.J.'s Robot <jjtolton@gmail.com>
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