Resource pack folder can be removed when game is paused

The bug

When you load a resource pack as a folder (not a .zip file) but don't access anything from it, you can remove it while the game it paused.
The problem is that if you try to access something from it afterwards errors will happen.

How to reproduce

1. Unzip External sound test (unzip).zip and load it in Minecraft
2. While the game is paused, delete or rename the resource pack
3. Resume the game and try to use the following command

   /playsound sound_plugin:blaze.burning_blaze ambient @p