The bug

Under very specific circumstances, you can get the incorrect number of items displayed in your inventory caused by picking up and simultaneously drinking a honey bottle.

Steps to reproduce

1. Fill your inventory completely up
2. Have between 2 and 63 glass bottles
3. Have 16 honey bottles
4. Harvest some honey (the bottle should go on the ground)
5. Stand above where the bottle landed
6. Drink a honey bottle. You will immediately pick up the honey bottle on the ground, making your item count actually be 16.  However, it will display as being 15 despite you actually really having 16. You did not lose the item, it was just incorrectly displayed.

Video

Attached.