How to fix Angular 2 `Uncaught (in promise): TypeError: Cannot read property 'query' of null`?

Question

I\'ve been using the Heroes tutorial in the Angular 2 docs to experiment. However, I\'ve come to a point that I don\'t understand what\'s happening with this error:

Answer 1

In my case, I fix this problem using @Inject decorator. Try this:

import {Inject} from '@angular/core'

constructor(@Inject(HeroService) private _heroService: HeroService,
            @Inject(RouteParams) private _routeParams: RouteParams) {}

My project is configured with JSPM and this is the only way to work with dependency injection, I do not why, anyone has an explanation?

Edited: I have found the solution. In my case, I have to add this configuration into config.js file

System.config({
 baseURL: "",
 defaultJSExtensions: true,
 transpiler: "typescript",
 typescriptOptions: {
    "target": "es5",
    "emitDecoratorMetadata": true
 },
 paths: {
    "npm:*": "jspm_packages/npm/*",
 ....

Now I can remove @Inject decorator and this sentence works properly

constructor(private _heroService: HeroService,
            private _routeParams: RouteParams) {}

The key is emitDecoratorMetadata: true