Thanks again for reporting! This one’s pretty bad, but it was a quick fix. A new build has been published that fixes this. Frankly I’m surprised this wasn’t discovered a while ago, since it’s been an issue from the start as far as I can tell and the steps to reproduce aren’t an uncommon scenario.
The problem was that a dead unit was being selected by default when nothing else was being hovered. In your video you can see the slime as the other hovered unit when you attack the obstacle. The game tries to start combat with the unit that’s already dead and finds that it doesn’t exist, so it blows up. This might have been undiscovered for a while since it doesn’t seem to crash when targeting other units, only non-unit targets. This shouldn’t occur anymore with the newest version.
Thank you again! Your videos are extremely helpful in debugging these issues! :)