macosx: fix rare crash when changing video effects settings

modules/gui/macosx/VideoEffects.m

@@ -536,6 +536,7 @@ static VLCVideoEffects *_o_sharedInstance = nil;
         vlc_object_release(p_vout);
 
     vlc_object_t *p_filter = vlc_object_find_name(pl_Get(p_intf), psz_filter);
+    if (p_filter) {
         int i_type;
         i_type = var_Type(p_filter, psz_name);
         if (i_type == 0)
@@ -548,8 +549,8 @@ static VLCVideoEffects *_o_sharedInstance = nil;
         } else
             msg_Dbg(p_intf, "restart not needed");
 
-    if (p_filter)
         vlc_object_release(p_filter);
+    }
 }
 
 - (void)setVideoFilterProperty: (char *)psz_name forFilter: (char *)psz_filter integer: (int)i_value