unnecessary express.js return found

lambda/app.js

@@ -2,7 +2,7 @@ var https = require('https');
 const config = require('./config');
 // Load the SDK for JavaScript
 const AWS = require('aws-sdk');
-// Set the region 
+// Set the region
 console.log(config.DynamoDB_TABLE_NAME);
 AWS.config.update({region: `${config.DYNAMODB_TABLE_REGION}`});
 // Set the Dynamodb Table
@@ -23,10 +23,7 @@ let findDataBySerialNumber = ( values,callback ) => {
       }, (err, data) => {
         if (err) {
           console.log(err);
-          res.status(500).json({
-            message: 'Could not load your device info',
-          }).end();
-          callback( err );
+          callback( null, err );
         } else {
           //console.log(data.Count);
           callback( null, data );
@@ -36,7 +33,7 @@ let findDataBySerialNumber = ( values,callback ) => {
 
 // Put IoT cert info into Dynamodb
 let putCertinfo = ( iotcert, values,callback ) => {
-    
+
   dynamoDb.update({
     TableName: Device_TABLE_NAME,
     Key:{
@@ -59,7 +56,7 @@ let putCertinfo = ( iotcert, values,callback ) => {
 
 // Apply cert & Attach thing, policy
 let applycert = ( serialNumber, callback ) => {
-    
+
   AWS.config.update({region: config.region});
   var iot = new AWS.Iot();
   var params = {
@@ -69,10 +66,10 @@ let applycert = ( serialNumber, callback ) => {
   iot.createKeysAndCertificate(params, function(err, certdata) {
     console.log("certdata:");
     console.log(certdata);
-    
+
     if (err) console.log(err, err.stack); // an error occurred
     else{
-      
+
        // Create IoT Policy for above cert
        var params = {
         policyDocument: config.PILICY_DOCUMENT, /* required */
@@ -82,7 +79,7 @@ let applycert = ( serialNumber, callback ) => {
         if (err) console.log(err, err.stack); // an error occurred
         else{
           console.log(data);
-          
+
           // Attach policy for cert
           var params = {
             policyName: serialNumber, /* required */
@@ -91,7 +88,7 @@ let applycert = ( serialNumber, callback ) => {
           iot.attachPolicy(params, function(err, data) {
             if (err) console.log(err, err.stack); // an error occurred
             else {
-              
+
               // Create thing for cert
               var params = {
                 thingName: serialNumber, /* required */
@@ -105,13 +102,13 @@ let applycert = ( serialNumber, callback ) => {
               iot.createThing(params, function(err, data) {
                 if (err) console.log(err, err.stack); // an error occurred
                 else {
-                  
+
                   // Attach thing for cert
                   var params = {
                     principal: certdata.certificateArn, /* required */
                     thingName: serialNumber /* required */
                   };
-                 
+
                   iot.attachThingPrincipal(params, function(err, thingdata) {
                     if (err) console.log(err, err.stack); // an error occurred
                     else {
@@ -124,20 +121,20 @@ let applycert = ( serialNumber, callback ) => {
           });
         }
       });
-    }                
+    }
   });
 }
 
-// Get VeriSign Class 3 Public Primary G5 root CA certificate 
+// Get VeriSign Class 3 Public Primary G5 root CA certificate
 let getIoTRootCA = ( callback ) => {
   const RootCA_URL = config.RootCA_URL;
   https.get(RootCA_URL, ( response ) => {
-    
+
     var body = [];
     //console.log(response.statusCode);
     //console.log(response.headers);
     //console.log(response);
-    
+
     response.on('data', function (chunk) {
         body.push(chunk);
     });
@@ -147,12 +144,12 @@ let getIoTRootCA = ( callback ) => {
         //console.log(body.toString());
         callback( null, body.toString() );
     });
-    
+
   })
 }
 
 module.exports = {
-  
+
     findDataBySerialNumber,
     putCertinfo,
     getIoTRootCA,