fix(@angular/cli): do not error when apps is missing from the config

Author: sumitarora

packages/@angular/cli/utilities/app-utils.ts

@@ -1,7 +1,14 @@
+const SilentError = require('silent-error');
+const chalk = require('chalk');
+
 import { CliConfig } from '../models/config';
 
 export function getAppFromConfig(nameOrIndex?: String) {
   const apps: any[] = CliConfig.getValue('apps');
+  if (!apps) {
+    throw new SilentError(chalk.red('Unable to find any apps in `.angular-cli.json`.'));
+  }
+
   let app = apps[0];
   if (nameOrIndex) {
     if (nameOrIndex.match(/^[0-9]+$/)) {