Update

autoload/vimtex/include.vim

@@ -63,6 +63,8 @@ function! s:input(fname, type) abort " {{{1
   if l:lnum == 0 | return a:fname | endif
 
   let l:cmd = vimtex#cmd#get_at(l:lnum, l:cnum)
+  if empty(l:cmd) | return a:fname | endif
+
   let l:file = join(map(
         \   get(l:cmd, 'args', [{}]),
         \   "get(v:val, 'text', '')"),

autoload/vimtex/re.vim

@@ -20,7 +20,7 @@ let g:vimtex#re#tex_input_import =
 let g:vimtex#re#tex_input_package =
       \ '\v\\%(usepackage|RequirePackage)%(\s*\[[^]]*\])?\s*\{\zs[^}]*\ze\}'
 
-let g:vimtex#re#tex_input = '\v^\s*%(' . join([
+let g:vimtex#re#tex_input = '\v^\s*\zs%(' . join([
       \   g:vimtex#re#tex_input_latex,
       \   g:vimtex#re#tex_input_import,
       \ ], '|') . ')'

autoload/vimtex/syntax/load.vim

@@ -7,6 +7,8 @@ if !exists('g:polyglot_disabled') || index(g:polyglot_disabled, 'latex') == -1
 "
 
 function! vimtex#syntax#load#general() abort " {{{1
+  if !exists('b:vimtex_syntax') | return | endif
+
   " I don't see why we can't match Math zones in the MatchNMGroup
   if !exists('g:tex_no_math')
     syntax cluster texMatchNMGroup add=@texMathZones
@@ -64,6 +66,8 @@ endfunction
 
 " }}}1
 function! vimtex#syntax#load#packages() abort " {{{1
+  if !exists('b:vimtex_syntax') | return | endif
+
   try
     call vimtex#syntax#p#{b:vimtex.documentclass}#load()
   catch /E117:/

autoload/vimtex/view/common.vim

@@ -153,9 +153,10 @@ function! s:xwin_template.xwin_exists() dict abort " {{{1
   " If xwin_id is unset, check if matching viewer windows exist
   "
   if self.xwin_id == 0
-    if has_key(self, 'get_pid')
+    let l:pid = has_key(self, 'get_pid') ? self.get_pid() : 0
+    if l:pid > 0
       let cmd = 'xdotool search'
-            \ . ' --all --pid ' . self.get_pid()
+            \ . ' --all --pid ' . l:pid
             \ . ' --name ' . fnamemodify(self.out(), ':t')
       let self.xwin_id = get(split(system(cmd), '\n'), 0)
     else

autoload/vimtex/view/zathura.vim

@@ -90,21 +90,20 @@ function! s:zathura.compiler_callback(status) dict abort " {{{1
 
   if !filereadable(self.out()) | return | endif
 
-  if g:vimtex_view_automatic
+  if g:vimtex_view_automatic && !has_key(self, 'started_through_callback')
     "
     " Search for existing window created by latexmk
-    "   It may be necessary to wait some time before it is opened and
-    "   recognized. Sometimes it is very quick, other times it may take
-    "   a second. This way, we don't block longer than necessary.
+    " Note: It may be necessary to wait some time before it is opened and
+    "       recognized. Sometimes it is very quick, other times it may take
+    "       a second. This way, we don't block longer than necessary.
     "
-    if !has_key(self, 'started_through_callback')
-      for l:dummy in range(30)
-        sleep 50m
-        if self.xwin_exists() | break | endif
-      endfor
-    endif
+    for l:dummy in range(30)
+      let l:xwin_exists = self.xwin_exists()
+      if l:xwin_exists | break | endif
+      sleep 50m
+    endfor
 
-    if !self.xwin_exists() && !has_key(self, 'started_through_callback')
+    if ! l:xwin_exists
       call self.start(self.out())
       let self.started_through_callback = 1
     endif