Use Syntax autocmd to apply syntax of fern

Author: lambdalisue

autoload/fern/internal/viewer.vim

@@ -57,6 +57,7 @@ function! s:init() abort
     autocmd! * <buffer>
     autocmd BufEnter <buffer> setlocal nobuflisted
     autocmd BufReadCmd <buffer> nested call s:BufReadCmd()
+    autocmd Syntax <buffer> call s:Syntax()
     autocmd ColorScheme <buffer> call s:ColorScheme()
     autocmd CursorMoved,CursorMovedI,BufLeave <buffer> let b:fern_cursor = getcurpos()[1:2]
   augroup END
@@ -99,9 +100,6 @@ function! s:init() abort
 
   " now the buffer is ready so set filetype to emit FileType
   setlocal filetype=fern
-  call helper.fern.renderer.syntax()
-  call fern#hook#emit('viewer:syntax', helper)
-  doautocmd <nomodeline> User FernSyntax
   call fern#action#_init()
 
   let l:Profile = fern#profile#start('fern#internal#viewer:init')
@@ -129,9 +127,6 @@ endfunction
 function! s:BufReadCmd() abort
   let helper = fern#helper#new()
   setlocal filetype=fern
-  call helper.fern.renderer.syntax()
-  call fern#hook#emit('viewer:syntax', helper)
-  doautocmd <nomodeline> User FernSyntax
   setlocal modifiable
   call setline(1, get(b:, 'fern_viewer_cache_content', []))
   setlocal nomodifiable
@@ -144,6 +139,13 @@ function! s:BufReadCmd() abort
         \.catch({ e -> fern#logger#error(e) })
 endfunction
 
+function! s:Syntax() abort
+  let helper = fern#helper#new()
+  call helper.fern.renderer.syntax()
+  call fern#hook#emit('viewer:syntax', helper)
+  doautocmd <nomodeline> User FernSyntax
+endfunction
+
 function! s:ColorScheme() abort
   let helper = fern#helper#new()
   call helper.fern.renderer.highlight()