patch 8.2.4609: :unhide does not check for failing to close a window

Problem:    :unhide does not check for failing to close a window.
Solution:   When closing a window fails continue with the next one.  Do not
            try closing the autocmd window. (closes #9984)

src/buffer.c

@@ -5334,13 +5334,17 @@ ex_buffer_all(exarg_T *eap)
 			    ? wp->w_height + wp->w_status_height < Rows - p_ch
 							     - tabline_height()
 			    : wp->w_width != Columns)
-		    || (had_tab > 0 && wp != firstwin)) && !ONE_WINDOW
-			     && !(wp->w_closing || wp->w_buffer->b_locked > 0))
+			|| (had_tab > 0 && wp != firstwin))
+		    && !ONE_WINDOW
+		    && !(wp->w_closing || wp->w_buffer->b_locked > 0)
+		    && !win_unlisted(wp))
 	    {
-		win_close(wp, FALSE);
-		wpnext = firstwin;	// just in case an autocommand does
-					// something strange with windows
-		tpnext = first_tabpage;	// start all over...
+		if (win_close(wp, FALSE) == FAIL)
+		    break;
+		// Just in case an autocommand does something strange with
+		// windows: start all over...
+		wpnext = firstwin;
+		tpnext = first_tabpage;
 		open_wins = 0;
 	    }
 	    else

src/proto/window.pro

@@ -46,6 +46,7 @@ win_T *win_horz_neighbor(tabpage_T *tp, win_T *wp, int left, long count);
 void win_enter(win_T *wp, int undo_sync);
 win_T *buf_jump_open_win(buf_T *buf);
 win_T *buf_jump_open_tab(buf_T *buf);
+int win_unlisted(win_T *wp);
 void win_free_popup(win_T *win);
 void win_remove(win_T *wp, tabpage_T *tp);
 int win_alloc_lines(win_T *wp);

src/testdir/test_autocmd.vim

@@ -3,6 +3,7 @@
 source shared.vim
 source check.vim
 source term_util.vim
+import './vim9.vim' as v9
 
 func s:cleanup_buffers() abort
   for bnr in range(1, bufnr('$'))
@@ -2975,4 +2976,18 @@ func Test_Changed_ChangedI()
   bw!
 endfunc
 
+func Test_closing_autocmd_window()
+  let lines =<< trim END
+      edit Xa.txt
+      tabnew Xb.txt
+      autocmd BufEnter Xa.txt unhide 1
+      doautoall BufEnter
+  END
+  call v9.CheckScriptFailure(lines, 'E814:')
+  au! BufEnter
+  only!
+  bwipe Xa.txt
+  bwipe Xb.txt
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    4609,
 /**/
     4608,
 /**/

src/window.c

@@ -43,7 +43,6 @@ static int frame_minheight(frame_T *topfrp, win_T *next_curwin);
 static int may_open_tabpage(void);
 static int win_enter_ext(win_T *wp, int flags);
 static void win_free(win_T *wp, tabpage_T *tp);
-static int win_unlisted(win_T *wp);
 static void win_append(win_T *after, win_T *wp);
 static void frame_append(frame_T *after, frame_T *frp);
 static void frame_insert(frame_T *before, frame_T *frp);
@@ -5233,7 +5232,7 @@ win_free(
  * Return TRUE if "wp" is not in the list of windows: the autocmd window or a
  * popup window.
  */
-    static int
+    int
 win_unlisted(win_T *wp)
 {
     return wp == aucmd_win || WIN_IS_POPUP(wp);