Deleting a belt makes it collapse into a trashpile

Issue:
When deleting a belt, part of it collapsed into a trash pile on the ground. I was not digging anywhere near it.

Expected:
Delete the selected belt without collapsing

Reproduce:

1. Open the save file (the camera should be at the right location).
   canary-belt-bug-before.save
2. Delete the steel belt as shown in the picture:
   
3. Observe the trash.

Version:
Update 1 0.5.1 (200)