When trying to buy mech armor trough a hexagon core (ive tried multiple) i get this lua crash

As said before this crash happens on buying mech armor, this is a multiplayer game with only the RPG mod added. (this crash also happens without the RPG mod). thus far we havent had any issue with any other item.

See imgur link for screenshot of the crash, See wetransfer link for a save of the map (this link is only working for 3 days, i can make a new link if needed)
https://imgur.com/a/GMN6r20
https://we.tl/t-GHGaX8X9xdDYdYN9

had this happen too, speciffically 2 tesla defenses to 5 mech armor, but only the first time

This was caused by trades occasionally trying to include coins, based on the "Coin Trade Chance" setting. It's fixed for Hextorio 1.9.0, and the setting is working as intended now (it was broken by a recent change to trade generation logic).