Bug/Issue "No Mail", Icon Pops Up

So I wake up and see that there's some mail waiting for me. I reach the mailbox and click it and... It says I have no mail? The icon is now gone and there's a new quest in my log, but it says there's no mail and I couldn't even read the letter!

I have some test characters and one main character I just started, but still got pretty far for where I am, and on at least one of the Test characters, the mailbox works perfectly! It just seems to be the main character that can't access the mailbox at all and that's the part that's kind of making me irate.

I have a ton of mods, I know, and one of them is almost guaranteed to be causing this issue, but I really want to know which one could be doing it. I'm posting my SMAPI log and a pastebin to the error that pops up when I attempt to open the mailbox, as well as my current savefile for anyone who wants to dig deeper and see what it could be:

https://smapi.io/log/6f5d9826512243738f085ab9db085fb6
https://pastebin.com/rhvECDZu

Thanks for the help and I hope we can fix this, if not for me, then for others in the future!