我正试图创建一个简单的表单，如http://angularjs.blogspot.no/2015/03/forms-in-angular-2.html所述。但是，当我添加
import {forms, required} from 'angular2/forms';
时，它会崩溃。请注意，保留HTML标记。TypeError: Cannot read property 'annotations' of undefined
TypeError: Cannot read property 'annotations' of undefined
at ReflectionCapabilities.System.register.execute.$__export.annotations (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/reflection/reflection_capabilities.es6!eval:81:40)
at Reflector.System.register.execute.$__export.annotations (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/reflection/reflector.es6!eval:81:50)
at DirectiveMetadataReader.System.register.execute.$__export.read (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/compiler/directive_metadata_reader.es6!eval:31:41)
at eval (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/compiler/compiler.es6!eval:127:35)
at Array.map (native)
at Function.System.register.execute.$__export.map (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/facade/collection.es6!eval:172:26)
at Compiler.System.register.execute.$__export.createSteps (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/compiler/compiler.es6!eval:126:43)
at Compiler.System.register.execute.$__export._compileTemplate (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/compiler/compiler.es6!eval:164:53)
at eval (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/compiler/compiler.es6!eval:154:29)
at Zone.run (http://localhost:9090/node_modules/zone.js/zone.js:87:19)
-----async gap-----
Error
at Function.System.register.execute.$__export.then (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/facade/async.es6!eval:35:28)
at Compiler.System.register.execute.$__export._compile (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/compiler/compiler.es6!eval:153:42)
at Compiler.System.register.execute.$__export.compile (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/compiler/compiler.es6!eval:134:34)
at eval (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/application.es6!eval:73:23)
at Function.System.register.execute.$__export.apply (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/facade/lang.es6!eval:317:23)
-----async gap-----
Error
at _AsyncInjectorStrategy.System.register.execute._AsyncInjectorStrategy.instantiate (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/di/injector.es6!eval:297:17)
at Injector.System.register.execute.$__export._getByKey (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/di/injector.es6!eval:138:33)
at Injector.System.register.execute.$__export.asyncGet (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/di/injector.es6!eval:112:25)
at eval (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/application.es6!eval:113:39)
-----async gap-----
Error
at VmTurnZone.System.register.execute.$__export._createInnerZone (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/zone/vm_turn_zone.es6!eval:61:45)
at new VmTurnZone (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/zone/vm_turn_zone.es6!eval:29:34)
at _createVmZone (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/application.es6!eval:101:16)
at bootstrap (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/application.es6!eval:110:16)
at y.main (http://localhost:9090/app.js!eval:10:12)
at http://localhost:9090/?:42:21
-----async gap-----
Error
at VmTurnZone.System.register.execute.$__export._createInnerZone (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/zone/vm_turn_zone.es6!eval:61:25)
at new VmTurnZone (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/zone/vm_turn_zone.es6!eval:29:34)
at _createVmZone (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/application.es6!eval:101:16)
at bootstrap (http://localhost:9090/node_modules/angular/dist/js/prod/es6/angular2/src/core/application.es6!eval:110:16)
at y.main (http://localhost:9090/app.js!eval:10:12)
at http://localhost:9090/?:42:21
无法理解错误消息的含义，也找不到定义表单指令的位置。
更新：'undefined' 实际上是一个 'forms' 指令，在 angular2/modules/angular2/src/forms 中确实缺失。然后 DirectiveMetadataReader将 'undefined' 传递给 reflector，最终导致异常。在 Template 中进行检查会很好。