vim-patch:8.2.0235: draw error when an empty group is removed from 'statusline'

Problem:    Draw error when an empty group is removed from 'statusline'.
Solution:   Do not use highlighting from a removed group.
dbe5d361fe

src/nvim/buffer.c

@@ -3531,6 +3531,12 @@ int build_stl_str_hl(
         if (n == curitem && group_start_userhl == group_end_userhl) {
           out_p = t;
           group_len = 0;
+          // do not use the highlighting from the removed group
+          for (n = groupitems[groupdepth] + 1; n < curitem; n++) {
+            if (items[n].type == Highlight) {
+              items[n].type = Empty;
+            }
+          }
         }
       }