Well, after digging around a bit, it looks like it’s from the More Armors mod (ID: More_Armors); Forum-link and GitHub-link.
So you’ll have to ask there for an update/fix (or from whereever else you’ve downloaded it).
After you’ve let them know, you can try to fix it yourself (if you want) by opening More_Armor/armor.json in your mods folder and change all the bodypart words on every "covers": line to the respective lowercase one from this list:
"head"
"eyes"
"mouth"
"torso"
"arm_l"
"arm_r"
"hand_l"
"hand_r"
"leg_l"
"leg_r"
"foot_l"
"foot_r"
Unless I’ve forgot something here - which’s quite possible - it should work afterwards.