When production is 0, the text shown on the pop up is
"Not ?????? structures built"

That might not be true.
For example, if there was a artifact struture(probably gates and processor) on a mining planet, and someone put a stripcore on it. Neutralizing the bonus but technically the building is still there

This might also be the case when slave barrier is on a planet but it's too horrible so never saw it in action.

Nothing much and no real impact but~ still wrong

Yeah, this was mentioned when they first came out. It might take more work than seems worth it.

ah~
haven't really used the forum long enough to know all the history...

but for all intents and purposes, simply replacing the line with "No xxxxx production aviliable" or something would be fine I think.

nah... it just needs to be re-worded to say "None from Artifact structures built"
(just add in the yellow text)

or heck,... don't even have a different wording for 0 production... just say... From Structures: 0
all that would require would be deleting a bit of code