vim-patch:9.1.1518: getcompletiontype() may crash (#34819)

Problem:  getcompletiontype() crashes when no completion is available
          (after v9.1.1509).
Solution: Don't call set_expand_context() (zeertzjq)

fixes: vim/vim#17681
closes: vim/vim#17684

e2c0f81dd0

src/nvim/eval.lua

@@ -3760,8 +3760,8 @@ M.funcs = {
       |getcmdprompt()|, |getcmdcomplpat()| and |setcmdline()|.
       Returns an empty string when completion is not defined.
 
-      To get the type of the command-line completion for the
-      specified string, use |getcompletiontype()|.
+      To get the type of the command-line completion for a specified
+      string, use |getcompletiontype()|.
     ]=],
     name = 'getcmdcompltype',
     params = {},