Bug 1542484 - fix some warnings when creating a News account. r=jorgk

mailnews/base/prefs/content/AccountWizard.js

@@ -448,12 +448,14 @@ function finishAccount(account, accountData)
     var srcServer = accountData.incomingServer;
     copyObjectToInterface(destServer, srcServer, true);
 
-    // see if there are any protocol-specific attributes
-    // if so, we use the type to get the IID, QueryInterface
-    // as appropriate, then copy the data over
-    dump("srcServer.ServerType-" + srcServer.type + " = " +
-         srcServer["ServerType-" + srcServer.type] + "\n");
-    if (srcServer["ServerType-" + srcServer.type]) {
+    // See if there are any protocol-specific attributes.
+    // If so, we use the type to get the IID, QueryInterface
+    // as appropriate, then copy the data over.
+    const typeProperty = "ServerType-" + srcServer.type;
+    let serverAttrs = (typeProperty in srcServer) ?
+                      srcServer[typeProperty] : null;
+    dump(`srcServer.${typeProperty} = ${serverAttrs}\n`);
+    if (serverAttrs) {
       // handle server-specific stuff
       var IID;
       try {

mailnews/base/prefs/content/aw-incoming.js

@@ -64,11 +64,8 @@ function incomingPageInit() {
   {
     var newsServer = document.getElementById("newsServer");
     var pageData = parent.GetPageData();
-    try
-    {
+    if (pageData.newsserver && pageData.newsserver.hostname)
       newsServer.value = pageData.newsserver.hostname.value;
-    }
-    catch (ex){}
   }
 
   var incomingServerbox = document.getElementById("incomingServerbox");