It wouldn't invalidate a lot of old code - see my argument and earlier discussion. If anyone thinks otherwise then let's hear a counter argument.
Again, the intention with this change is _not_ to force people to add catches. That since it throws only errors that one typically doesn't want to handle anyway. These are bail-out-and-die errors we're talking about, just like out-of-memory etc. I.e. the kind of errors that one usually handles in a catch-all clause at the top of the thread, as the master already does.
An improved exception system is therefore not a prerequisite. If these were errors needing catching, I wouldn't accept this change any more than Zino, new fancy exception system or not.
So imo it's not much of a compatibility issue. It is a little one, and that's why I made the change in the development version only. But it's way smaller than e.g. the continually better type checking (which is great, btw). Really, there are many a lot more incompatible things in 7.7 than this. Several libraries, believed to be unused, have been dropped completely, for instance.
Still, it would probably be prudent to add #pike 7.6 compatibility versions. I could do that.
Oh, I already did. Good.