attempting to switch to a resource pack and the game crashes

Put the summary of the bug you're having here
game crashing when atempting to switch to a converted resource pack
What I expected to happen was...: switch to resorce pack
Describe what you thought should happen here

What actually happened was...:
Describe what happened here

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. ...
3. ...