First slot not cleared for insertion after using key

[Darkere]

Minecraft Version:
1.16.5

Forge Version:
1.16.5-36.1.16

Mod Version:
simpletomb-1.16.5-1.0.7

When opening a grave using the key, the first slot (the slot the key was in) becomes empty instead of being filled by the item that was in that slot before death. This causes all items to shift forcing me to reorganize my inventory.

[NeosGhost]

still present in 1.19

[SaintWacko]

As a developer, I can guess what's happening here. When you activate the gravestone, two things happen. First, your inventory is restored from the gravestone, shifted over depending on what slots are already filled (this includes the slot filled by the key). Second, the key is removed from your inventory. The solution should be as simple as reversing the order of those two actions.