So, that crash in the log looks like its caused by a vanilla function, with the RE patch being up the stack getting the blame.

My suspicion is that this is causes by the module thats right above it ("Bathroom 4")

I think the module thats getting constructed either connects to the rocket above or vice versa, causing the game method that trires registering the rocket to the rocket platform to crash

I assume that this crash would not show up if the rocketplatform 830 in the screenshot is 1 tile lower so the two spacefarer modules arent connected directly

Yep, that's exactly it! Moved it one space down and works! Can't believe I didn't catch that after building the first two rows.

User error.

Thank you so much! Now I can fit 48 Duplicants in that rectangle. :D

I assume its a race condition, aka a "triggers sometimes" bug that simply didnt happen on the first time.
glad to hear that solved it