Problem: `TSHighlighter:destroy()` causes double-processing of the modeline
and failure of `b:undo_ftplugin`.
Solution: Disable modeline in `TSHighlighter:destroy()` by setting `modeline=false`
if executing `syntaxset` autocommands for the `FileType` event.
Co-authored-by: Daniel Petrovic <daniel.petrovic@ebcont.com>