Fix some codefactor warnings

www/js/app.js

@@ -1515,8 +1515,6 @@ define(['jquery', 'zimArchiveLoader', 'uiUtil', 'settingsStore','abstractFilesys
         }
     }
 
-    var messageChannel;
-
     var libzimWebWorker = new Worker("a.out.js");
 
     /**
@@ -1568,7 +1566,7 @@ define(['jquery', 'zimArchiveLoader', 'uiUtil', 'settingsStore','abstractFilesys
                         messagePort.postMessage({ 'action': 'giveContent', 'title': title, 'content': '' });
                     } else if (dirEntry.isRedirect) {
                         var redirectPath = dirEntry.redirectPath;
-                        // Ask the ServiceWork to send an HTTP redirect to the browser.
+                        // Ask the ServiceWorker to send an HTTP redirect to the browser.
                         // We could send the final content directly, but it is necessary to let the browser know in which directory it ends up.
                         // Else, if the redirect URL is in a different directory than the original URL,
                         // the relative links in the HTML content would fail. See #312