[gimp/gimp-2-10] app: don't dereference NULL image pointer

[Michael Natterer <mitch src gnome org>]

commit f16f3b56d47ad03f97eadf673a14e881ecde2b43
Author: Michael Natterer <mitch gimp org>
Date:   Sun May 5 15:36:07 2019 +0200

    app: don't dereference NULL image pointer
    
    windows_menu_display_query_tooltip(): bail out if "image" is
    NULL. Can't happen currently but did happen temporarily while hacking
    on related code. Better safe than sorry.
    
    (cherry picked from commit 3bf2a3c16603f434521cf94c1e2fd7d745a18794)

 app/menus/windows-menu.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/app/menus/windows-menu.c b/app/menus/windows-menu.c
index 80cbd99363..28d891a044 100644
--- a/app/menus/windows-menu.c
+++ b/app/menus/windows-menu.c
@@ -415,6 +415,9 @@ windows_menu_display_query_tooltip (GtkWidget  *widget,
   gint       width;
   gint       height;
 
+  if (! image)
+    return;
+
   text = gtk_widget_get_tooltip_text (widget);
   gtk_tooltip_set_text (tooltip, text);
   g_free (text);