Warped and Crimson hanging signs uses their respective plank sounds, despite their stripped stems having unique sounds

Nether hanging signs uses a combination of chain sound and the nether plank sound when they break, which is incorrect as they are crafted out of stripped stems, and nether stems have a different sound than the planks.

Steps to reproduce
1. Break a nether stem. Observe it's sound.
2. Break a nether hanging sign, Observe how it's sound is of the nether planks and not of nether stems.