patch 8.2.0327: crash when opening and closing two popup terminal windows

Problem:    Crash when opening and closing two popup terminal windows.
Solution:   Check that prevwin is valid. (closes #5707)

src/popupwin.c

@@ -2114,9 +2114,31 @@ popup_close_and_callback(win_T *wp, typval_T *arg)
 #ifdef FEAT_TERMINAL
     if (wp == curwin && curbuf->b_term != NULL)
     {
-	// Closing popup window with a terminal: put focus back on the previous
-	// window.
+	win_T *owp;
+
+	// Closing popup window with a terminal: put focus back on the first
+	// that works:
+	// - another popup window with a terminal
+	// - the previous window
+	// - the first one.
+	for (owp = first_popupwin; owp != NULL; owp = owp->w_next)
+	    if (owp != curwin && owp->w_buffer->b_term != NULL)
+		break;
+	if (owp != NULL)
+	    win_enter(owp, FALSE);
+	else
+	{
+	    for (owp = curtab->tp_first_popupwin; owp != NULL;
+							     owp = owp->w_next)
+		if (owp != curwin && owp->w_buffer->b_term != NULL)
+		    break;
+	    if (owp != NULL)
+		win_enter(owp, FALSE);
+	    else if (win_valid(prevwin))
 		win_enter(prevwin, FALSE);
+	    else
+		win_enter(firstwin, FALSE);
+	}
     }
 #endif
 

src/testdir/test_terminal.vim

@@ -2391,6 +2391,17 @@ func Test_terminal_in_popup()
   call delete('XtermPopup')
 endfunc
 
+func Test_double_popup_terminal()
+  let buf1 = term_start(&shell, #{hidden: 1})
+  let win1 = popup_create(buf1, {})
+  let buf2 = term_start(&shell, #{hidden: 1})
+  let win2 = popup_create(buf2, {})
+  call popup_close(win1)
+  call popup_close(win2)
+  exe buf1 .. 'bwipe!'
+  exe buf2 .. 'bwipe!'
+endfunc
+
 func Test_issue_5607()
   let wincount = winnr('$')
   exe 'terminal' &shell &shellcmdflag 'exit'

src/version.c

@@ -738,6 +738,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    327,
 /**/
     326,
 /**/