If you are not sure whether you have found a bug, here are some guidelines:
asbug. Reliable assemblers never crash.
asproduces an error message for valid input, that is a bug.
asdoes not produce an error message for invalid input, that is a bug. However, you should note that your idea of “invalid input” might be our idea of “an extension” or “support for traditional practice”.
asare welcome in any case.