In
- type: STR_LOBSTERMAN_MELEE_WEAPON
specialUseEmptyHand: true
specialUseEmptyHandShow: true
bigSprite: 70
meleeSound: 42
strengthApplied: true
damageType: 7
accuracyMelee: 100
tuMelee: 15
battleType: 3
fixedWeapon: true
invWidth: 2
invHeight: 3
clipSize: -1
recover: false
1/ either delete `bigSprite: 70`
2/ or change it to `bigSprite: { mod: xcom2, index: 70 }`
3/ or remove the entire STR_LOBSTERMAN_MELEE_WEAPON entry, since it is identical to vanilla xcom2
In general, don't copy stuff from parent mods, unless you have a good reason to do so.
It is enough (and preferred) to only write the changes.
PS: some other items have the same issue, you may need to change them too...