Hi, I just discovered a run-time error: When a solar tower gets directly replaced with one of a different quality tier, it will crash the game to the menu if there are any mirrors in range of it and directed at it. Error message below:

The mod Cheese's Concentrated Solar (0.4.3) caused a non-recoverable error.
Please report this error to the mod author.

Error while running event ch-concentrated-solar::on_built_entity (ID 6)
ch-concentrated-solar/control/database.lua:89: DATABASE CORRUPTION: Mirror is linked to an invalid tower
stack traceback:
[C]: in function 'assert'
ch-concentrated-solar/control/database.lua:89: in function 'link_mirror_to_tower'
ch-concentrated-solar/control/database.lua:169: in function 'link_mirror_to_tower_if_closer'
ch-concentrated-solar/control/database.lua:403: in function 'on_built_entity_callback'
ch-concentrated-solar/control.lua:49: in function <ch-concentrated-solar/control.lua:48>

Quality brings me only pain.. will fix tomorrow morning.

I share the sentiment. XD