The bug

After a dimension has been loaded once, removing the dimension file inside a data pack, removing or disabling the data pack, does not disable the dimension. Additionally, no errors will be shown in the log.

This is especially annoying when you are developing dimensions and you make a mistake. The dimension will act like it is unmodified. It will use a cached version of the worldgen settings in level.dat.

How to reproduce

1. Download the attached data pack MC-198209-1.18.zip. This adds one new dimension.
2. Teleport to the custom dimension

   /execute in blip:foo run tp @s ~ ~ ~

3. Disable or completely remove the data pack
4. Save the world, and re-join
   Notice that you are still in the dimension