patch 9.0.0882: using freed memory after SpellFileMissing autocmd uses bwipe

Problem:    Using freed memory after SpellFileMissing autocmd uses bwipe.
Solution:   Bail out if the window no longer exists.

src/spell.c

@@ -2110,8 +2110,8 @@ did_set_spelllang(win_T *wp)
 	    {
 		spell_load_lang(lang);
 		// SpellFileMissing autocommands may do anything, including
-		// destroying the buffer we are using...
+		// destroying the buffer we are using or closing the window.
-		if (!bufref_valid(&bufref))
+		if (!bufref_valid(&bufref) || !win_valid_any_tab(wp))
 		{
 		    ret_msg = N_(e_spellfilemising_autocommand_deleted_buffer);
 		    goto theend;

src/testdir/test_spell.vim

@@ -159,6 +159,19 @@ func Test_spell_file_missing()
   %bwipe!
 endfunc
 
+func Test_spell_file_missing_bwipe()
+  " this was using a window that was wiped out in a SpellFileMissing autocmd
+  set spelllang=xy
+  au SpellFileMissing * n0
+  set spell
+  au SpellFileMissing * bw
+  snext somefile
+
+  au! SpellFileMissing
+  bwipe!
+  set nospell spelllang=en
+endfunc
+
 func Test_spelldump()
   " In case the spell file is not found avoid getting the download dialog, we
   " would get stuck at the prompt.

src/version.c

@@ -695,6 +695,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    882,
 /**/
     881,
 /**/