check requires

Author: mattn

autoload/lsp_settings.vim

@@ -561,6 +561,16 @@ function! s:vim_lsp_load_or_suggest(ft) abort
       continue
     endif
 
+    let l:missing = 0
+    for l:require in l:server.requires
+      if !executable(l:require)
+        let l:missing = 1
+        break
+      endif
+    endfor
+    if l:missing !=# 0
+      continue
+    endif
     let l:command = lsp_settings#get(l:server.command, 'cmd', [])
     if empty(l:command) && !lsp_settings#executable(l:server.command)
       let l:script = printf('%s/%s.vim', s:checkers_dir, l:server.command)