Referencing non-existent file Internal error

[UltraDaiSenpai]

[Window Title]
Error

[Main Instruction]
An internal error occured:

[Content]
referencing a nonexistant file
Please save your work (use 'save as' to so you don't overwrite things)
and restart Magic Set Editor.

You should leave a bug report on https://github.com/twanvl/MagicSetEditor2/issues/
Press Ctrl+C to copy this message to the clipboard.

Call stack:
[00] 00007FF6C3F55567
[01] 00007FF6C3F59784
[02] 00007FF6C3F59C80
[03] 00007FF6C3DB7493
[04] 00007FF6C3D9BC8C
[05] 00007FF6C3DD7BF5
[06] 00007FF6C3E14C47
[07] 00007FF6C3E16B0C
[08] 00007FF6C3F5E3C2
[09] 00007FF6C3F5CB01
[10] 00007FF6C3EB745D
[11] 00007FF6C3EF53EC
[12] 00007FF6C41412B4
[13] 00007FF6C416FFB4
[14] 00007FF6C41711E3
[15] 00007FF6C416FEB8
[16] 00007FF6C3FD357E
[17] 00007FF6C416FF0C
[18] 00007FF6C4170D3A
[19] 00007FF6C4029CB4
[20] 00007FF6C407EC2B

[OK]

It's slightly different than the other ones I've seen here so far, so I figured I would post it.