patch 8.2.2464: using freed memory if window closed in autocommand

Problem:    Using freed memory if window closed in autocommand. (houyunsong)
Solution:   Check the window still exists.

src/ex_cmds.c

@@ -2768,7 +2768,9 @@ do_ecmd(
 		did_decrement = close_buffer(oldwin, curbuf,
 			 (flags & ECMD_HIDE) ? 0 : DOBUF_UNLOAD, FALSE, FALSE);
 
-		the_curwin->w_closing = FALSE;
+		// Autocommands may have closed the window.
+		if (win_valid(the_curwin))
+		    the_curwin->w_closing = FALSE;
 		--buf->b_locked;
 
 #ifdef FEAT_EVAL

src/testdir/test_autocmd.vim

@@ -2726,4 +2726,15 @@ func Test_BufNew_arglocal()
   au! BufNew
 endfunc
 
+func Test_autocmd_closes_window()
+  au BufNew,BufWinLeave * e %e
+  file yyy
+  au BufNew,BufWinLeave * ball
+  call assert_fails('n xxx', 'E143:')
+
+  bwipe %
+  au! BufNew
+  au! BufWinLeave
+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 */
+/**/
+    2464,
 /**/
     2463,
 /**/