[gnome-font-viewer] font-widget: fix a potential memory leak

[Cosimo Cecchi <cosimoc src gnome org>]

commit f7e57b3e63d6c1675d313cd5d02d6f010ede8dd3
Author: Cosimo Cecchi <cosimoc gnome org>
Date:   Fri Jul 5 11:49:05 2019 -0700

    font-widget: fix a potential memory leak
    
    Always clear self->sample_string here.

 src/sushi-font-widget.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/src/sushi-font-widget.c b/src/sushi-font-widget.c
index f85b9e0..3c1189c 100644
--- a/src/sushi-font-widget.c
+++ b/src/sushi-font-widget.c
@@ -329,10 +329,10 @@ set_pango_sample_string (SushiFontWidget *self)
       retval = TRUE;
   }
 
-  if (retval) {
-    g_free (self->sample_string);
+  g_clear_pointer (&self->sample_string, g_free);
+
+  if (retval)
     self->sample_string = g_strdup (sample_string);
-  }
 
   return retval;
 }