When a Searchlight is built next to turrets by bots, a non-recoverable error occurs.
Of note: This was done with Bob's warfare T4 Laser turrets (which shouldn't be the issue), and the Searchlight was connected to a Circuit network during it's construction (Undid a deconstruction)
The error is as follows:

Error while running event SearchlightAssault::on_robot_built_entity (ID 14)
SearchlightAssault/control-tunion.lua:396:attempt to index local 'g' (a nil value)
stack traceback:
SearchlightAssault/control-tunion.lua396:in function 'IsBoostableAndInRange'
SearchlightAssault/control-tunion.lua407:in function 'Createrelationship'
SearchlightAssault/control-tunion.lua305:in function 'TurretAdded'
SearchlightAssault/control.lua447:in function <SearchlightAssault/control.lua:433>

Wait, I got the crash to repeat, it was caused by a bot building the searchlight then the turret.

Thanks for reporting this! Sadly, I don't know when I'll be able to get a fix out.

In the meantime, if you know the name of the turret, there's an option in the mod settings to make a blocklist that stops searchlights from trying to mess with other mod's turrets.

To add one or more turrets to the block list:
- Look up the name of the incompatible turret
- You can either check the mod's .lua files for the entity prototype, or try using this simple in-game command while hovering your mouse over the turret in question:
- /c game.print(game.player.selected.name)
- Load your game
- Pause the game, and enter the Settings menu
- Enter the Mod Settings menu, then the Map tab
- Locate the SearchlightAssault mod settings option "Ignore turrets matching these semi-colon separated names:"
- Write the entity / prototype name exactly, including hypens (-), etc
- To add more turrets, put a semicolon (;) between each entry
- Confirm changes and exit the pause menu
- Resume playing

Note that changes made in the mod settings menu will be lost unless you save your game.