Complain about stray echo lines in the codebase

plugin/ale.vim

@@ -24,8 +24,8 @@ endif
 if !s:has_features
     " Only output a warning if editing some special files.
     if index(['', 'gitcommit'], &filetype) == -1
-        echoerr 'ALE requires NeoVim >= 0.1.5 or Vim 8 with +timers +job +channel'
-        echoerr 'Please update your editor appropriately.'
+        execute 'echoerr ''ALE requires NeoVim >= 0.1.5 or Vim 8 with +timers +job +channel'''
+        execute 'echoerr ''Please update your editor appropriately.'''
     endif
 
     " Stop here, as it won't work.