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.

src/buffer.c

@@ -4216,6 +4216,10 @@ build_stl_str_hl(
 		{
 		    p = t;
 		    l = 0;
+		    // do not use the highlighting from the removed group
+		    for (n = groupitem[groupdepth] + 1; n < curitem; n++)
+			if (item[n].type == Highlight)
+			    item[n].type = Empty;
 		}
 	    }
 	    if (l > item[groupitem[groupdepth]].maxwid)

src/testdir/dumps/Test_statusline_1.dump

@@ -0,0 +1,10 @@
+> +0&#ffffff0@49
+|~+0#4040ff13&| @48
+|~| @48
+|~| @48
+|~| @48
+|~| @48
+|~| @48
+|~| @48
+| +3#0000000&|Q|≡| @46
+| +0&&@49

src/testdir/test_statusline.vim

@@ -8,6 +8,7 @@
 
 source view_util.vim
 source check.vim
+source screendump.vim
 
 func s:get_statusline()
   return ScreenLines(&lines - 1, &columns)[0]
@@ -393,3 +394,22 @@ func Test_statusline_visual()
   bwipe! x1
   bwipe! x2
 endfunc
+
+func Test_statusline_removed_group()
+  CheckScreendump
+
+  let lines =<< trim END
+    scriptencoding utf-8
+    set laststatus=2
+    let &statusline = '%#StatColorHi2#%(✓%#StatColorHi2#%) Q≡'
+  END
+  call writefile(lines, 'XTest_statusline')
+
+  let buf = RunVimInTerminal('-S XTest_statusline', {'rows': 10, 'cols': 50})
+  call term_wait(buf, 100)
+  call VerifyScreenDump(buf, 'Test_statusline_1', {})
+
+  " clean up
+  call StopVimInTerminal(buf)
+  call delete('XTest_statusline')
+endfunc

src/version.c

@@ -742,6 +742,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    235,
 /**/
     234,
 /**/