I tried to remove a belt balancer on my factory and every time I try to remove it my game crashes with this error message:

The mod Belt Balancer 2 (2.0.9) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event belt-balancer-2::on_player_mined_entity (ID 74)
belt-balancer-2/objects/part.lua:215: attempt to index local 'belt' (a nil value)
stack traceback:
belt-balancer-2/objects/part.lua:215: in function 'remove'
belt-balancer-2/control.lua:145: in function <belt-balancer-2/control.lua:134>

The error only occours when I remove this specific belt

I too have had this issue, it's also triggering if a belt is placed going into (and only into) the balancer

Same thing,

The mod Belt Balancer 2 (2.0.9) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event belt-balancer-2::on_player_mined_entity (ID 74)
belt-balancer-2/objects/part.lua:265: attempt to index local 'belt' (a nil value)
stack traceback:
belt-balancer-2/objects/part.lua:265: in function 'remove'
belt-balancer-2/control.lua:145: in function <belt-balancer-2/control.lua:134>

And if you disconnect adjacent belts from it and then reconnect them, that gives you another crash (didn't catch it tho)