Waiting for head to load before inserting banner

content.js

@@ -394,8 +394,18 @@ function main(mutations = null, observer = null) {
                     } else {
                       newURL = 'https://' + site["destination_base_url"];
                     }
-                    // Notify that another wiki is available
+                    // When head elem is loaded, notify that another wiki is available
+                    const docObserver = new MutationObserver(function (mutations, mutationInstance) {
+                      const headElement = document.querySelector('head');
+                      if (headElement) {
                         displayRedirectBanner(newURL, site['id'], site['destination'], storage);
+                        mutationInstance.disconnect();
+                      }
+                    });
+                    docObserver.observe(document, {
+                      childList: true,
+                      subtree: true
+                    });
                   }
                 }
               }