linepos type should be dict actually

Ref:
- https://github.com/vim-jp/vim-vimlparser/blob/377b6cd4a901b80e6051ab930583479210f9d729/autoload/vimlparser.vim#L521
- https://github.com/vim-jp/vim-vimlparser/blob/377b6cd4a901b80e6051ab930583479210f9d729/autoload/vimlparser.vim#L3774

Author: haya14busa

autoload/vimlparser.vim

@@ -285,7 +285,7 @@ function! s:ExArg()
   let ea.force_ff = 0
   let ea.force_enc = 0
   let ea.bad_char = 0
-  let ea.linepos = []
+  let ea.linepos = {}
   let ea.cmdpos = []
   let ea.argpos = []
   let ea.cmd = {}