patch 9.1.0039: too vague errors for 'listchars'/'fillchars'

Problem:  too vague errors for 'listchars'/'fillchars'
Solution: Include the field name in error message.
          (zeertzjq)

related: neovim/neovim#27050
closes: #13877

Co-authored-by: Cole Frankenhoff <cole.nhf@gmail.com>
Signed-off-by: zeertzjq <zeertzjq@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/proto/screen.pro b/src/proto/screen.pro
index b4f54a2..53937d3 100644
--- a/src/proto/screen.pro
+++ b/src/proto/screen.pro
@@ -55,8 +55,8 @@
 int number_width(win_T *wp);
 int screen_screencol(void);
 int screen_screenrow(void);
-char *set_fillchars_option(win_T *wp, char_u *val, int apply);
-char *set_listchars_option(win_T *wp, char_u *val, int apply);
+char *set_fillchars_option(win_T *wp, char_u *val, int apply, char *errbuf, size_t errbuflen);
+char *set_listchars_option(win_T *wp, char_u *val, int apply, char *errbuf, size_t errbuflen);
 char_u *get_fillchars_name(expand_T *xp, int idx);
 char_u *get_listchars_name(expand_T *xp, int idx);
 char *check_chars_options(void);