terrminated by signal 11" error because the GCCollect() process isn't finished
Are you sure that's the case?
The problem with the signal 11 handler is that it catches the seg fault, handles it nicely, but in turn makes it hard to see where it went wrong - ie. if you try running your mini example it will probably not stop at the seg fault point.
It is possible to disable that handler, so that running it through gdb will allow you to pinpoint the exact location of the error (although, depending on where the error occurs this may or may not be helpful to you - eg. if it breaks in a library, fine, if it breaks in BlitzMax generated assm, bad luck).