[mutter] clutter/offscreen-effect: Don't ever early out out of post paint

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 223f0337805ae2ef3da3e8c92a3acffc5766efbe
Author: Jonas Ådahl <jadahl gmail com>
Date:   Tue Mar 31 19:42:47 2020 +0200

    clutter/offscreen-effect: Don't ever early out out of post paint
    
    If we would, we'd miss popping the framebuffer from the pant context
    framebuffer stack.
    
    https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1166

 clutter/clutter/clutter-offscreen-effect.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)
---
diff --git a/clutter/clutter/clutter-offscreen-effect.c b/clutter/clutter/clutter-offscreen-effect.c
index ac4ea98e2..0b81c67a8 100644
--- a/clutter/clutter/clutter-offscreen-effect.c
+++ b/clutter/clutter/clutter-offscreen-effect.c
@@ -446,13 +446,16 @@ clutter_offscreen_effect_post_paint (ClutterEffect       *effect,
   ClutterOffscreenEffectPrivate *priv = self->priv;
   CoglFramebuffer *framebuffer;
 
-  if (priv->offscreen == NULL ||
-      priv->target == NULL ||
-      priv->actor == NULL)
-    return;
+  g_warn_if_fail (priv->offscreen);
+  g_warn_if_fail (priv->target);
+  g_warn_if_fail (priv->actor);
 
   /* Restore the previous opacity override */
-  clutter_actor_set_opacity_override (priv->actor, priv->old_opacity_override);
+  if (priv->actor)
+    {
+      clutter_actor_set_opacity_override (priv->actor,
+                                          priv->old_opacity_override);
+    }
 
   framebuffer = clutter_paint_context_get_framebuffer (paint_context);
   cogl_framebuffer_pop_matrix (framebuffer);