XWIKI-19204: Annotation JS code is failing when the More Actions menu is disabled

* register the annotations handler only when the annotations trigger is available

xwiki-platform-core/xwiki-platform-annotation/xwiki-platform-annotation-ui/src/main/resources/AnnotationCode/Script.xml

@@ -727,7 +727,9 @@
   hookMenuButton : function() {
     // Since 7.4M1, the annotations trigger is inserted via an UIX.
     var annotationsTrigger = $('tmAnnotationsTrigger');
-    annotationsTrigger.observe('click', this.toggleSettingsPanel.bind(this));
+    if (annotationsTrigger) {
+      annotationsTrigger.observe('click', this.toggleSettingsPanel.bind(this));
+    }
  },
 
   setAnnotationVisibility : function (visibility) {