Fix a couple of coffee to js conversion blunders

lib/db.js

@@ -831,7 +831,7 @@ function getDueTasks(deviceId, timestamp, callback) {
           if (res[0]) {
             if (!task.fileType) task.fileType = res[0].metadata.fileType;
 
-            if (task.fileName)
+            if (!task.fileName)
               task.fileName = res[0].filename || res[0]._id.toString();
           }
 

lib/soap.js

@@ -501,7 +501,7 @@ function faultStruct(xml) {
 
 function fault(xml) {
   let faultCode, faultString, detail;
-  for (const c of xml.childNodes) {
+  for (const c of xml.childNodes()) {
     switch (c.name()) {
       case "faultcode":
         faultCode = c.text();
@@ -546,14 +546,16 @@ function request(data, cwmpVersion, warn) {
     }
   }
 
-  for (const c of headerElement.childNodes()) {
-    switch (c.name()) {
-      case "ID":
-        rpc.id = c.text();
-        break;
-      case "sessionTimeout":
-        rpc.sessionTimeout = parseInt(c.text());
-        break;
+  if (headerElement) {
+    for (const c of headerElement.childNodes()) {
+      switch (c.name()) {
+        case "ID":
+          rpc.id = c.text();
+          break;
+        case "sessionTimeout":
+          rpc.sessionTimeout = parseInt(c.text());
+          break;
+      }
     }
   }