Fix $slr->is_ambiguous() to throw exception when there is not parse
Fix $slr->is_ambiguous() to throw exception when there is not parse

pczarn/kollos,jeffreykegler/libmarpa,pczarn/kollos,jeffreykegler/libmarpa,jeffreykegler/kollos,jeffreykegler/kollos,jeffreykegler/kollos,jeffreykegler/libmarpa,jeffreykegler/libmarpa,pczarn/kollos,jeffreykegler/libmarpa,pczarn/kollos,pczarn/kollos,jeffreykegler/kollos,jeffreykegler/kollos