A bit more context - it happened when I finished the lvl or clicked next.
Viewing post in QUACK!!! on ICE jam comments
Oh! I figured it out today, and I will upload the new version after the jam which will fix this bug.
This issue will only occur when you click the next level button and click a duck simultaneously, and the entity will be prematurely despawned. Another system relies on this entity will try to insert a bundle to an invalid entity, which will cause a crash. So I just have to make sure that the two systems are executed in the right order to fix the bug.
Thanks a lot for your valuable feedback!