patch 9.1.1518: getcompletiontype() may crash

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

fixes: #17681
closes: #17684

Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/proto/usercmd.pro b/src/proto/usercmd.pro
index d0cd2a3..dcf2a1d 100644
--- a/src/proto/usercmd.pro
+++ b/src/proto/usercmd.pro
@@ -9,7 +9,7 @@
 char_u *get_user_cmd_flags(expand_T *xp, int idx);
 char_u *get_user_cmd_nargs(expand_T *xp, int idx);
 char_u *get_user_cmd_complete(expand_T *xp, int idx);
-char_u *cmdcomplete_type_to_str(int expand);
+char_u *cmdcomplete_type_to_str(int expand, char_u *arg);
 int cmdcomplete_str_to_type(char_u *complete_str);
 char *uc_fun_cmd(void);
 int parse_compl_arg(char_u *value, int vallen, int *complp, long *argt, char_u **compl_arg);