The function number: 1951, 1943, 478
The complete error text An item with the same key has already been added Object reference not set to an instance of an object
The window affected main screen
What you were doing at the time Finishing a battle at the NPR homeworld (though there was some NPR-NPR fighting somewhere else in the galaxy just before the error)
Conventional or TN start TN
Random or Real Stars Real
Is your decimal separator a comma? No. US Layout
Is the bug is easy to reproduce, intermittent or a one-off? Second time it happened, but since I suspect it's NPR related, I don't think I can reproduce on command.
If this is a long campaign - say 75 years or longer - let me know the length of the campaign as well 65 years into a game.
The only other "unusual" thing happening is I have some ships massively overloaded with survivors I picked up from destroying the NPRs commercial shipping.
I am facing the same situation now.
I was not involved in a fight, nor am carrying survivors. Also, the only NPR in the game was shot back to the stone age a century ago, and has only just been able to build ships again a couple years back.
I was just advancing time hoping my next Sensor tech would finish before another round of Spoilers spawned.
After watching it for dozens of 1-day increments, these 3 errors popped up. Now, any attempt at advancing time causes me to have to click through these 3 errors ~50 times apiece.
(I'm about 250years into the game)