The mod Electric Trains (1.3.5) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event ElectricTrains::on_player_mined_entity (ID 67)
ElectricTrains/control.lua:149: attempt to index field 'currently_burning' (a nil value)
stack traceback:
ElectricTrains/control.lua:149: in function <ElectricTrains/control.lua:147>

To reproduce:
- start Factorio 1.1.104, with only ElectricTrains 1.3.5 installed
- start new sandbox scenario, with all tech researched (and yes to all other questions)
- place rail and Electric locomotive on it
- enter loco and drive it empty, until it stops
- leave loco
- manually mine loco (right click)
- crash :)

The same happens when the loco is mined by a construction robot.

A workaround is to recharge the train first, eg. by attaching another loco and have the train go to a train stop.

The crash does not happen in 1.3.4, so manually downloading 1.3.4 and installing it to the mods directory is another workaround :)

Fixed! Thank you for the report.

Thanks for fixing =)