Crash after klicking a light which hangs in the air after removing wall

[Eldermann]

I removed a wall and a light still hangs in the air. there was no message that the wall could not be removed because of installed parts.
Now the light hangs in the air of nothing. When I click the light the game immediately crashes, repeatedly.
I can provide a save game just before the removal to repeat this error.

Here is crashdump and a screenshot