The bug

When you delete a resource pack you used lately, Minecraft does not update the options.txt file causing crash reports to contain wrong information.

How to reproduce

1. Download the attached resource pack
2. Load it in Minecraft
3. Close Minecraft
4. Delete the resource pack
5. Open Minecraft again and close it (to make sure it did not remove the resource pack from the options.txt file)
6. Open the options.txt file
   → You will see that the resource pack is still listed as active resource pack.