If you are not sure whether you have found a bug, here are some guidelines:
as bug. Reliable assemblers never crash.
as produces an error message for valid input, that is a bug.
as does 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”.
as are welcome in any case.