Sounds doesn't work in Minecraft Classic c0.30_01c

Summary of Issue

In Minecraft Classic c0.30_01c, sounds are not played, even if they are downloaded and existing ( they are mapped to the resources folder )

Reproduction Steps

1. Launch the latest launcher version.
2. Choose the custom Minecraft Classic c0.30_01c version.
3. Launch it.
4. Notice, that no sounds are played ( no walk sounds, block break sounds ).

A pull request is already ready to be merged on Mojang's GitHub.
https://github.com/Mojang/LegacyLauncher/pull/32

This pull request also includes:

• A way of toggling survival mode on or off using the same jar.
• The fix for saving and loading versions.
• Custom game resolution (with --width and --height).
• Connect to a server using the version's JSON file.

Consider setting this to low priority.
I'm unsure if I selected the good component.