Angular2 の quickstart を試していたら GET /traceur 404 (Not Found) が出て二進も三進も行かなくなった場合の対応方法

取り急ぎ、

$ npm install plugin-typescript --save

plugin-typescript をインストールして、

$ git diff systemjs.config.js
diff --git a/systemjs.config.js b/systemjs.config.js
index ...
--- a/systemjs.config.js
+++ b/systemjs.config.js
@@ -4,9 +4,28 @@
  */
 (function (global) {
   System.config({
+    transpiler: 'ts',
+    typescriptOptions: {
+      // Copy of compiler options in standard tsconfig.json
+      target: 'es5',
+      module: 'commonjs',
+      moduleResolution: 'node',
+      sourceMap: true,
+      emitDecoratorMetadata: true,
+      experimentalDecorators: true,
+      lib: [ 'es2015', 'dom' ],
+      noImplicitAny: true,
+      suppressImplicitAnyIndexErrors: true
+    },
+    meta: {
+      typescript: {
+        exports: 'ts'
+      }
+    },
     paths: {
       // paths serve as alias
       'npm:': 'node_modules/'
     },
     // map tells the System loader where to look for things
     map: {
@@ -24,8 +43,10 @@
       '@angular/forms': 'npm:@angular/forms/bundles/forms.umd.js',

       // other libraries
       rxjs: 'npm:rxjs',
+      ts: 'npm:plugin-typescript/lib/plugin.js',
+      typescript: 'npm:typescript/lib/typescript.js',
       'angular-in-memory-web-api': 'npm:angular-in-memory-web-api/bundles/in-memory-web-api.umd.js'
     },
     // packages tells the System loader how to load when no filename and/or no extension
     packages: {
       app: {
-        main: './main.js',
-        defaultExtension: 'js'
+        main: './main.ts',
+        defaultExtension: 'ts'
       },
       rxjs: {
         defaultExtension: 'js'

systemjs.config.js を修正する。