[gimp] app: get rid of a wrong return-after-free report.

[Jehan <jehanp src gnome org>]

commit fd9f96f174ab84262561dc33e574f0b13b513e8f
Author: Jehan <jehan girinstud io>
Date:   Fri Oct 1 12:40:10 2021 +0200

    app: get rid of a wrong return-after-free report.
    
    Reported by Massimo, though this one is wrong, as far as I can see.
    
    `ninja scan-build` apparently reports `result` as being returned after
    being freed here. But actually since we are setting the `error` with
    g_set_error() in the same time we free `result`, we would also enter the
    `if (*error)` block a few lines later, which would return NULL and not
    `result` anyway. I guess the static analyzer could not see that far.
    
    Still, set the pointer to NULL with g_clear_pointer(), which should be
    enough to make the static analyzer happy.

 app/propgui/gimppropgui-eval.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/app/propgui/gimppropgui-eval.c b/app/propgui/gimppropgui-eval.c
index 548bc1adc8..6951d51ea4 100644
--- a/app/propgui/gimppropgui-eval.c
+++ b/app/propgui/gimppropgui-eval.c
@@ -655,7 +655,7 @@ 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_clear_pointer (&result, g_free);
     }
 
   g_free (t);