Don't read CSS file when it was deleted

[mskelton]

In Neovim when using the Tailwind language server, deleting a CSS file results in the following error:

[ERROR][2023-04-21 21:06:00] ...lsp/handlers.lua:535    "Unhandled exception: ENOENT: no such file or directory, open '/my/file/path/hi.css'\nError: ENOENT: no such file or directory, open '/my/file/path/hi.css'"

This is happening due to the LSP attempting to read from the now deleted CSS file during file watch changes. I updated the code that was reading from the CSS files to first ensure that it wasn't a Deleted change event.

[bradlc]

Nice catch, thank you!