[gimp/gimp-2-10] app: in gimp_prop_eval_string(), don't leak result upon trailing tokens

[Ell <ell src gnome org>]

commit 5605e8484cba278fe335ce783c90a4e13a6ccec7
Author: Ell <ell_se yahoo com>
Date:   Mon Jun 1 22:38:10 2020 +0300

    app: in gimp_prop_eval_string(), don't leak result upon trailing tokens
    
    (cherry picked from commit ae801871e5007f67ec50ae2d58894998c8e21176)

 app/propgui/gimppropgui-eval.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/app/propgui/gimppropgui-eval.c b/app/propgui/gimppropgui-eval.c
index c36476001d..422578b13d 100644
--- a/app/propgui/gimppropgui-eval.c
+++ b/app/propgui/gimppropgui-eval.c
@@ -647,6 +647,8 @@ gimp_prop_eval_string_impl (GObject      *config,
     {
       g_set_error (error, GIMP_PROP_EVAL_ERROR, GIMP_PROP_EVAL_FAILED,
                    "invalid expression");
+
+      g_free (result);
     }
 
   g_free (t);