in the ghost ship chest's loot table, "weight" is missing for "wooden_box", I checked other loot table files and the "weight" is present, so I think it is missing by mistake, this is what is looks like:
...
{
"type": "minecraft:item",
"weight": 20,
"name": "mineminenomi:pirate_cutlass"
},
{
"type": "minecraft:item",
"weight": 20,
"name": "mineminenomi:den_den_mushi"
},
{
"type": "minecraft:item",
"name": "mineminenomi:wooden_box"
},
...