title: NullInjectorError: StaticInjectorError(BootModule)[BsDropdownDirective -> AnimationBuilder]: NullInjectorError: No provider for AnimationBuilder
body: <p>i'am working with angular 8 and and the version 5.3.2 of ngx-bootstrap, i would implement a navbar but i had a problem of a  " NullInjectorError: StaticInjectorError(BootModule)" for every ngx-bootstrap's module added</p>
  
  <p>app.component.html</p>
  
  <pre><code>&lt;nav class="navbar navbar-default"&gt;
    &lt;div class="container-fluid"&gt;
      &lt;div class="navbar-header"&gt;
        &lt;button type="button" class="navbar-toggle collapsed" (click)="isCollapsed = !isCollapsed" aria-expanded="false"&gt;
          &lt;span class="sr-only"&gt;Toggle navigation&lt;/span&gt;
          &lt;span class="icon-bar"&gt;&lt;/span&gt;
          &lt;span class="icon-bar"&gt;&lt;/span&gt;
          &lt;span class="icon-bar"&gt;&lt;/span&gt;
        &lt;/button&gt;
      &lt;/div&gt;
  
      &lt;div class="collapse navbar-collapse" [collapse]=isCollapsed&gt;
        &lt;ul class="nav navbar-nav"&gt;
          &lt;li class="active"&gt;&lt;a href="#"&gt;Link &lt;span class="sr-only"&gt;(current)&lt;/span&gt;&lt;/a&gt;&lt;/li&gt;
          &lt;li&gt;&lt;a href="#"&gt;Link&lt;/a&gt;&lt;/li&gt;
          &lt;li class="dropdown" dropdown&gt;
   &lt;a href="#" dropdownToggle class="dropdown-toggle"&gt;Dropdown &lt;span class="caret"&gt;&lt;/span&gt;&lt;/a&gt;
    &lt;ul *dropdownMenu class="dropdown-menu" role="menu"&gt;
      &lt;li role="menuitem"&gt;&lt;a class="dropdown-item" href="#"&gt;Action&lt;/a&gt;&lt;/li&gt;
    &lt;/ul&gt;
  &lt;/li&gt;
        &lt;/ul&gt;
        &lt;ul class="nav navbar-nav navbar-right"&gt;
                 &lt;li class="dropdown" dropdown&gt;
   &lt;a href="#" dropdownToggle class="dropdown-toggle"&gt;Dropdown &lt;span class="caret"&gt;&lt;/span&gt;&lt;/a&gt;
    &lt;ul *dropdownMenu class="dropdown-menu" role="menu"&gt;
      &lt;li role="menuitem"&gt;&lt;a class="dropdown-item" href="#"&gt;Action&lt;/a&gt;&lt;/li&gt;
      &lt;li role="menuitem"&gt;&lt;a class="dropdown-item" href="#"&gt;Another action&lt;/a&gt;&lt;/li&gt;
      &lt;li role="menuitem"&gt;&lt;a class="dropdown-item" href="#"&gt;Something else here&lt;/a&gt;&lt;/li&gt;
      &lt;li class="divider dropdown-divider"&gt;&lt;/li&gt;
      &lt;li role="menuitem"&gt;&lt;a class="dropdown-item" href="#"&gt;Separated link&lt;/a&gt;
      &lt;/li&gt;
    &lt;/ul&gt;
  &lt;/li&gt;
        &lt;/ul&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  &lt;/nav&gt;
  
  </code></pre>
  
  <p>app.component.ts</p>
  
  <p><code>isCollapsed = true;</code> </p>
  
  <p>and the app.module.ts</p>
  
  <pre><code>import { NgModule } from '@angular/core';
  import { FormsModule } from '@angular/forms';
  import { AppComponent } from './app.component';
  import { AppRoutingModule } from './app.routing';
  import { CommonModule } from '@angular/common';
  import { NgbAccordionModule } from '@ng-bootstrap/ng-bootstrap';
  import { CollapseModule, BsDropdownModule } from 'ngx-bootstrap';
  
  
  @NgModule({
    imports: [
      CommonModule,
      FormsModule,
      AppRoutingModule,
      HttpClientModule,
      NgbAccordionModule,
      CollapseModule.forRoot(),
      BsDropdownModule.forRoot()
    ],
    declarations: [
      AppComponent
    ],
    bootstrap: [AppComponent]
  })
  export class AppModule {}
  </code></pre>