[devhelp] DhSettings: add missing g_returns to public functions

[Sébastien Wilmet <swilmet src gnome org>]

commit 3ef793333a7901290a8ccd7d56119d06acea9ba5
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Fri Apr 28 17:05:32 2017 +0200

    DhSettings: add missing g_returns to public functions

 src/dh-settings.c |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)
---
diff --git a/src/dh-settings.c b/src/dh-settings.c
index 2ce89cd..d5998fb 100644
--- a/src/dh-settings.c
+++ b/src/dh-settings.c
@@ -150,30 +150,35 @@ dh_settings_free_singleton (void)
 GSettings *
 dh_settings_peek_window_settings (DhSettings *self)
 {
+        g_return_val_if_fail (DH_IS_SETTINGS (self), NULL);
         return self->priv->settings_window;
 }
 
 GSettings *
 dh_settings_peek_paned_settings (DhSettings *self)
 {
+        g_return_val_if_fail (DH_IS_SETTINGS (self), NULL);
         return self->priv->settings_paned;
 }
 
 GSettings *
 dh_settings_peek_contents_settings (DhSettings *self)
 {
+        g_return_val_if_fail (DH_IS_SETTINGS (self), NULL);
         return self->priv->settings_contents;
 }
 
 GSettings *
 dh_settings_peek_assistant_settings (DhSettings *self)
 {
+        g_return_val_if_fail (DH_IS_SETTINGS (self), NULL);
         return self->priv->settings_assistant;
 }
 
 GSettings *
 dh_settings_peek_fonts_settings (DhSettings *self)
 {
+        g_return_val_if_fail (DH_IS_SETTINGS (self), NULL);
         return self->priv->settings_fonts;
 }
 
@@ -184,6 +189,7 @@ dh_settings_get_selected_fonts (DhSettings  *self,
 {
         gboolean use_system_font;
 
+        g_return_if_fail (DH_IS_SETTINGS (self));
         g_return_if_fail (font_name_fixed != NULL && *font_name_fixed == NULL);
         g_return_if_fail (font_name_variable != NULL && *font_name_variable == NULL);