After i destroyed the last green assembler, i get the 2 messages, and after i close the last one i get the error.
Maybe it's because i tried to game the scenario a bit by not destroying the green assemblers until i had all 3 bases disabled and looted.
The last green assembler i destroyed is the north one (the one you're probably going for second, not last) , i don't know if that's relevant.
I updated my mods but still the same error (but my save was from standing right next to the last assembler to destroy so maybe something was already screwy at that point?).
i had 2 other mods active (bottleneck and vehicle snapping) but the error persisted even after deactivating both.
Anyway, here's the error:
The scenario level caused a non-recoverable error.
Please report this error to the scenario author.
Error while running event level::on_tick (ID 0)
Must provide either a 'position' or 'target'
stack traceback:
[C]: in function 'set_controller'
...Data/Roaming/Factorio/temp/currently-playing/control.lua:590: in function 'init'
core/lualib/story.lua:56: in function 'story_update'
...Data/Roaming/Factorio/temp/currently-playing/control.lua:1493: in function <...Data/Roaming/Factorio/temp/currently-playing/control.lua:1490>
Edit: destroying the last 2 assemblers in the 'correct' order didn't change anything.