The mod Quality Control (2.4.0) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event quality-control::on_configuration_changed
The mod Transport Belt Direction Indicator (1.0.1) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event belt-direction-indicator::on_runtime_mod_setting_changed (ID 71)
belt-direction-indicator/control.lua:25: bad argument #2 of 2 to 'get_player' (string expected, got nil)
stack traceback:
[C]: in function 'get_player'
belt-direction-indicator/control.lua:25: in function <belt-direction-indicator/control.lua:22>
stack traceback:
[C]: in function 'newindex'
__quality-control/control.lua:166: in function 'migrate_upgrade_limits_to_runtime_settings'
quality-control/control.lua:436: in function <quality-control/control.lua:434>

Removing Transport Belt Direction removed the error

Thanks for reporting this jivaii!

I posted the fix for the other mod to their forum. Any mod that raises runtime configuration changes would cause Transport Belt Direction Indicator to throw an error, but it's a simple fix on their end.