title: Angular 4 Drop Down Error With Simple Usage
body: <p>I tried using the Angular 4 Drop Down:</p>
  
  <p><a href="https://www.npmjs.com/package/ng4-material-dropdown" rel="nofollow noreferrer">https://www.npmjs.com/package/ng4-material-dropdown</a></p>
  
  <p>Here is what I have as my div element:</p>
  
  <pre><code>&lt;ng4-dropdown&gt;
    &lt;ng4-dropdown-menu&gt;
      &lt;ng4-menu-item *ngFor="let item of items"&gt;
        {{ item }}
      &lt;/ng4-menu-item&gt;
    &lt;/ng4-dropdown-menu&gt;
  &lt;/ng4-dropdown&gt;
  </code></pre>
  
  <p>My items is contained in the corresponding typescript class and I have added the imports to the NgModule as below (my app.module.ts):</p>
  
  <pre><code>@NgModule({
    declarations: [
      AppComponent,
      HomeComponent,
      FooterComponent,
      HeaderComponent,
      LoginComponent,
      RegisterComponent
    ],
    imports: [
      SharedModule,
      BrowserModule,
      Ng4DropdownModule,
      routing
    ],
    providers: [
      ApiService,
      AuthGuard,
      JwtService,
      AuthenticationService,
      AlertService,
      ProfilesService,
      UserService,
      // providers used to create fake backend
      fakeBackendProvider,
      MockBackend,
      BaseRequestOptions
    ],
    bootstrap: [AppComponent]
  })
  export class AppModule { }
  </code></pre>
  
  <p>When I run my application, I get the following error:</p>
  
  <pre><code>TypeError: Cannot read property 'setGlobalVar' of null
      at _createNgProbe (ng4-dropdown.bundle.js:6944)
      at eval (module.ngfactory.js? [sm]:1)
      at _callFactory (core.es5.js:9561)
      at _createProviderInstance$1 (core.es5.js:9490)
      at initNgModule (core.es5.js:9441)
      at new NgModuleRef_ (core.es5.js:10555)
      at createNgModuleRef (core.es5.js:10539)
      at Object.debugCreateNgModuleRef [as createNgModuleRef] (core.es5.js:12833)
      at NgModuleFactory_.webpackJsonp.../../../core/@angular/core.es5.js.NgModuleFactory_.create (core.es5.js:13828)
      at core.es5.js:4497
  </code></pre>
  
  <p>This error seems to happen just by including the import to my NgModule, even without adding the div in my html component. Any ideas what this could be and how to fix this?</p>