Crash Log: here

Mods Loaded:
Fabric API 0.28.3+1.16
Iron Jetpacks 0.2.6
Cloth API 1.4.9
'Slight' GUI Modifications 1.6.1
Architectury 1.1.55

Issue:
When loading these mods together, the client crashes before reaching the title screen.

Steps used to test:
Disable Iron Jetpacks (all other mods enabled) = No Crash.
Disable 'Slight' GUI Modifications(all other mods enabled) = No Crash.
Enable both 'Slight' GUI Modifications and Iron Jetpacks = Game Crashes.

Edit:
This crash does not happen when using Iron Jetpacks 0.2.5. Hopefully, this will help narrow down the issue.