The mod Powered Belts (0.4.0) caused a non-recoverable error.
Please report this error to the mod author.
Error while running event PoweredBelts::on_tick (ID 0)
invalid key to 'next'
stack traceback:
[C]: in function 'next'
PoweredBelts/control.lua:39: in function <PoweredBelts/control.lua:35>
The error is hit and miss. On a new game for testing in sandbox if there is a similar type belt in the inventory when a belt is place / deleted then replaced the above error will generate. Other times it will not. Sometimes having only one belt will cause the error.