I used bluebuild to deconstruct a Reactor (the mod, by name) that was running and I soft crashed with this message:

2940.154 Error MainLoop.cpp:788: Exception at tick 20152513: Error while running event on_tick (ID 0)
LuaEntity API call when LuaEntity was invalid.
stack traceback:
Reactors/control.lua:318: in function 'update_reactor'
Reactors/control.lua:422: in function <Reactors/control.lua:415>
24665.198 Goodbye

So, I get that the problem here is probably that the update_reactor function doesn't know what to do when you pull the reactor out from under it, and they should decide how to handle that situation, but it occurs to me that this will happen to a lot of mods that interact with your software. If this is what I think it is, any mod that calls a custom timed update could lead to a crash. Don't know what you can about it, but thought I should let you know.

Cheers, let me know if I can help.

Looks entity.destroy() needs to be paired with a manual event call.

Some of my other mods (like concreep) always check if entities are still valid before doing anything. Looks like one of those cases where if one person goofs, everything is fine. If both goof, the world ends!

Updated to 0.7.0 with more events!