[airstrike] Bug in bonus system

[Erik Auerswald]

Hi,

> Hi. There should be a check to see if the missile has an ai before a
> message is sent to it.
> 
> ..
> + if (((struct missile *)obj)->ai)
> res = obj_message(((struct missile *)obj)->ai,msg);
> ..

Thanks.

> Unfortunately I have only access to internet-cafe type machines, and
> cannot commit a fix myself.

I've just committed the above change (with a little extension).

Erik