theme-check reports "full theme check" errors on removed files

[vfonic]

Repro steps:

1. Create/update (liquid) file with theme-check errors
2. Close the file in the VS Code editor
3. Remove the file without opening it (right click + Delete, or delete the whole directory where it's located, or rm ..., or remove in Finder)
4. Check PROBLEMS tab in VS Code

Expected:

The errors don't show errors from this non-existent file

Actual:

The errors show errors that were in this file before.

5. Run >Liquid Theme Check: Run Checks

The errors are still present.