(small) Demo Patch 1.7.10a

Oops, looks like a crash has slipped past our testing. Here's a quick patch to address that.

• Fix crash if clicking to resize a wall, but not moving the cursor.

The engine was just a bit too paranoid, thinking the world was on fire, and intentionally crashing to avoid state corruption... Except the edge case was just fine ^^; Sorry about that, and thanks or the crash reports, so we could quickly identify it and fix it <3

Cheers, Tom & Ana