I was testing this mod on a sandbox (Blueprint Sandbox), and when I cleanup the sandbox (with some towers deployed), the game crashed:

1497.854 Error MainLoop.cpp:1288: Exception at tick 217860648: The mod Cheese's Concentrated Solar (0.3.0) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event ch-concentrated-solar::on_nth_tick(12)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
[C]: in function 'index'
__ch-concentrated-solar/control-util.lua:346: in function 'removeMirrorFromTower'
ch-concentrated-solar/control-util.lua:405: in function 'notify_tower_invalid'
ch-concentrated-solar/control/nthtick.lua:95: in function <ch-concentrated-solar/control/nthtick.lua:56>

Thanks

Thanks for the report, currently unable to recreate this, I'm assuming you were using editor mode at the time?
When you were cleaning up, was that with the destruction blueprints, bots, or mining them one at a time?
Lastly, was time paused at the time? (stops some destruction/created events, has caused bugs in the past)
Thanks

I'm using the sandbox provided by the mod "Blueprint Sandbox" (https://mods.factorio.com/mod/blueprint-sandboxes), This mod offers a area where we can test some things... There are a button that clean the entire area of any buildings, resetting the entire surface. When I click on this button, with entities of this mod builded, the game crashed!
About how the cleaning it's done, I don't know. It simply delete everything on the surface!

Tell me here if I can help with any more information.

Thanks.

Found it, thanks!
Fixed for 0.3.1

You don't publish the update yet!

Thanks for the fix!