The mod Repair Turret (0.5.2) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event Repair_Turret::on_tick (ID 0)
Repair_Turret/script/repair_turret.lua:904: bad argument #1 of 2 to 'next' (table expected, got nil)
stack traceback:
[C]: in function 'next'
Repair_Turret/script/repair_turret.lua:904: in function 'update_turret'
Repair_Turret/script/repair_turret.lua:980: in function 'check_turret_update'
Repair_Turret/script/repair_turret.lua:1083: in function 'handler'
core/lualib/event_handler.lua:47: in function <core/lualib/event_handler.lua:45>

Not sure what happened. I just left the game running in the background and came back to this.

Managed to trigger it again with this just before the if:
log(serpent.line(turret_data))
This is the result:
{pickup_entity = {__self = "userdata"}, stack = {__self = "userdata"}, targets = {[4323463] = {__self = "userdata"}}, turret = {__self = "userdata"}}
{pickup_entity = {__self = "userdata"}, stack = {__self = "userdata"}, targets = {[4323463] = {__self = "userdata"}}, turret = {__self = "userdata"}}
{pickup_entity = {__self = "userdata"}, stack = {__self = "userdata"}, targets = {}, turret = {__self = "userdata"}}

I got the exact same error as the first message on this page.
I was constructing stuff and the error occured right at the moment a construction drone from your other mod constructed something, the green beam was still visible behind the popup.

Yep, same for me, it happened when I used the decon planner to remove some ghost tiles.

Same error, not sure exactly what triggered it, but it has happened multiple times.

should be fixed, thanks for the report