I managed to find a bug and softlock on desert level 1-9.
I tried using only the healer, because there’s something hidden there and I wondered if it was “don’t destroy something” again like desert 1-3.
When I did, the rats never ran up, and the tank-on-rails shot horizontally rather than towards me, and at the end of the level the boss never showed up. And Esc didn’t do anything.
(What is the secret on that level?)