Fixed js error in deleted/collapsed messages

diff --git a/wcfsetup/install/files/js/WoltLabSuite/Core/Ui/Mobile.js b/wcfsetup/install/files/js/WoltLabSuite/Core/Ui/Mobile.js
index f29cc392a0094a94eae02c181dac2655e0d33ec9..ef2aa240110f968f84efc6294ebb13b58dd3bdeb 100644 (file)
--- a/wcfsetup/install/files/js/WoltLabSuite/Core/Ui/Mobile.js
+++ b/wcfsetup/install/files/js/WoltLabSuite/Core/Ui/Mobile.js
@@ -167,7 +167,8 @@ define(
                                                        navigation.classList.toggle('open');
                                                }
                                        });
-                                       
+                               }
+                               if (navigation) {
                                        navigation.addEventListener(WCF_CLICK_EVENT, function(event) {
                                                event.stopPropagation();
                                        });