The Bug:
Mobs in their death animations produce the fire extinguishing sound every tick while being in lava while it's raining.
Steps to Reproduce:
Set the weather to "rain".
Summon a mob and place some lava on it.
Listen closely as the mob dies and enters it death animation.
Observed Behavior:
The fire extinguishing sound is played every tick.
Expected Behavior:
The fire extinguishing sound would not be played every tick.
Can confirm.