MythicMob Items -Error when loading and importing.
Summary
I've recently updated from 1.21.4 to 1.21.7 Mythicmob items that use the 'itemstack' format now no longer load, and produce an error on server startup.
opsa (Ones in green layout work. Red layout = do not load)
Steps to reproduce
Start server that has imported mythicmob items.
Current behavior See summary
Intended correct behavior
Mythicmob items should load.
Server log file
Full log: https://mclo.gs/rAODCHJ!
Debug log snippet
Short log: https://mclo.gs/HHiLoUh
Proposed fixes
For /mm import to work again, and for previously imported items to load.