I also have no idea of scripting really, but two things I can recommend:

1. Go to the workshop page of the mod and ask in the comments about the error.
2. Go to the official TTS discord and ask in the scripting section for help.

You should tell that to author of the workshop item.

However I could try to help with fix if you'll give me a link to that item

The author of the workshop item is me. The link is this: https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=2997563018

Okay, I see.
Method getObjectFromGUID() can't find object with GUID you provided to it ("4a5471") and it's returning nil. Attempting to use shuffle() on it throws an error.

You should provide it a GUID of item that exists.

Okay. I don't know what it means but I'll investigate... Thanks!

If you don't know scripting but the mod is scripted, then maybe ask the one who made the script for you? But if I read CSQRBs comment correctly, it seems to mean that the GUID (a unique reference to an object existing on the table) has somehow changed and you need to supply a new one in its place. You need to find out what the script is trying to reference to in that faulty line, then find that object on the table, check it's GUID (can be accessed with right click) and then adjust it in the script.

Okay.
I think it's a problem with the cards in the deck. From what I have read they give problems, and at some point before the error message appeared, I combined decks, added individual cards...