Hitting rabbits with fire aspect sword: Couldn't smelt 0xtile.air@0 because there is no smelting recipe

How to reproduce

1. Get a fire aspect sword

   /give @p diamond_sword 1 0 {ench:[{id:20s,lvl:1s}]}
   

2. Spawn some rabbits
3. Kill some rabbits
4. This message will appear in the console: Couldn't smelt 0xtile.air@0 because there is no smelting recipe

Seems to occur if a smeltable item isn't randomly dropped that time the rabbit is killed.