fix(@angular/cli): fix default app index

Author: sumitarora

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

@@ -1,6 +1,7 @@
 const SilentError = require('silent-error');
 const chalk = require('chalk');
 
+import { oneLine } from 'common-tags';
 import { CliConfig } from '../models/config';
 
 export function getAppFromConfig(nameOrIndex?: String) {
@@ -9,17 +10,21 @@ export function getAppFromConfig(nameOrIndex?: String) {
     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]+$/)) {
       const index = parseInt(nameOrIndex.toString(), 10);
-      app = apps[index];
+      if (apps[index]) {
+        return apps[index];
+      }
     } else {
       const filtered = apps.filter((currentApp: any) => currentApp.name === nameOrIndex);
       if (filtered.length > 0) {
-        app = filtered[0];
+        return filtered[0];
       }
     }
+  } else {
+    return apps[0];
   }
-  return app;
+  throw new SilentError(chalk.red(oneLine`Unable to find app with name or index. 
+    Make you have proper apps configuration in \`.angular-cli.json\``));
 }