To Reproduce
Immediately after logging into my test server, I went to my inventory and received a lovely GL wibbly.

Crash log
https://pastebin.com/iHvztX7R

Additional context
I had to do this quickly, within a few seconds of logging into the server in order to trigger it. The longer I wait, the more likely the crash doesn't happen, or the inventory merely glitches until I log out and back in. I can avoid the crash by giving it at least a minute before I try to access the inventory.