**Problem:** In the case where the user sets the treesitter foldexpr upon startup in
their `init.lua`, the fold info will be calculated before the parser has
been loaded in, meaning folds will be properly calculated until edits or
`:e`.
**Solution:** Refresh fold information upon `VimEnter` as a sanity check
to ensure that a parser really doesn't exist before always returning
`'0'` in the foldexpr.
6711fa27ca
