refactor(@angular-devkit/build-angular): error handling

Author: tiaguinho

packages/angular_devkit/build_angular/src/angular-cli-files/utilities/check-port.ts

@@ -5,7 +5,7 @@
  * Use of this source code is governed by an MIT-style license that can be
  * found in the LICENSE file at https://angular.io/license
  */
-const net = require('net');
+import * as net from 'net';
 
 export function checkPort(port: number, host: string, basePort = 49152): Promise<number> {
   return new Promise<number>((resolve, reject) => {
@@ -19,9 +19,7 @@ export function checkPort(port: number, host: string, basePort = 49152): Promise
       server.once('error', err => {
         if (port !== 0 && err.code === 'EADDRINUSE') {
           // If the port isn't available and we weren't looking for any port, throw error.
-          reject(`Port ${port} is already in use. Use '--port' to specify a different port.`);
-        } else if (port === 0) {
-          reject(err);
+          reject(new Error(`Port ${port} is already in use. Use '--port' to specify a different port.`));
         }
 
         _getPort(portNumber + 1);