more linting and add condition in case of no hash

lib/modules/swarm/embarkjs.js

@@ -11,7 +11,7 @@ __embarkSwarm.setProvider = function (options) {
   this.connectError = new Error(`Cannot connect to Swarm node on ${this.connectUrl}`);
   this._getUrl = options.getUrl || `${this.connectUrl}/bzzr:/`;
 
-  var promise = new Promise((resolve, reject) => {
+  return new Promise((resolve, reject) => {
     try {
       if (!this.bzz.currentProvider) {
         this.bzz.setProvider(`${options.protocol}://${options.host}:${options.port}`);
@@ -22,7 +22,6 @@ __embarkSwarm.setProvider = function (options) {
       reject(this.connectError);
     }
   });
-  return promise;
 };
 
 __embarkSwarm.isAvailable = function () {
@@ -72,9 +71,9 @@ __embarkSwarm.uploadFile = function (inputSelector) {
   }
 
   return new Promise((resolve, reject) => {
-    var reader = new FileReader();
+    const reader = new FileReader();
     reader.onloadend = (event) => {
-      var fileContent = new Uint8Array(event.target.result);
+      const fileContent = new Uint8Array(event.target.result);
       this.isAvailable().then((isAvailable) => {
         if (!isAvailable) {
           return reject(this.connectError);

lib/modules/swarm/upload.js

@@ -28,6 +28,9 @@ class Swarm {
           .catch(callback);
         },
         function printUrls(dir_hash, callback) {
+          if (!dir_hash) {
+            return callback('No directory hash was returned');
+          }
           console.log((`=== DApp available at ${self.storageConfig.getUrl}${dir_hash}/`).green);
 
           callback();
@@ -36,9 +39,9 @@ class Swarm {
         if (err) {
           console.log("error uploading to swarm".red);
           console.log(err);
-          reject(err);
+          return reject(err);
         }
-        else resolve('successfully uploaded to swarm');
+        resolve('successfully uploaded to swarm');
       });
     });
   }