Firework rockets are sometimes crafted with a flight duration of 1 regardless of the amount of gunpowder used

Steps to reproduce:

1. Create/open a world
2. Grab some paper and gunpowder
3. Attempt to craft firework rockets with a flight duration of 2/3

Observed result:
Sometimes the flight duration is set to 1, even though you're using 2/3 separate gunpowder.

Expected result:
The flight duration is always set to the correct amount.