title: TypeError: Converting circular structure to JSON property 'name' closes the circle
body: <p>I am using reactive forms in Angular 8 to insert data into the database, but I am getting this error <code>TypeError: Converting circular structure to JSON</code>. It is saying that <code>name</code> property is a circular structure and I am unable to find out why. Can anyone help me out? Thanks in advance.</p>
  
  <p><strong>my component.ts</strong></p>
  
  <pre class="lang-js prettyprint-override"><code>export class AddMainCategoryComponent implements OnInit {
      nm;
      desc;
      date;
  
      get name() {
          return this.addMCform.get('name')
      }
  
      get description() {
          return this.addMCform.get('description')
      }
      constructor(public mainCategoryService: MainCategoryService, private fb: FormBuilder) { }
  
      addMCform = this.fb.group({
          name: ['', [Validators.required, Validators.minLength(3)]],
          description: ['']
      })
  
      ngOnInit() {
      }
  
      addMain_categories() {
          let main_category = {
              nm: this.name,
              desc: this.description,
              date: new Date(),
  
          }
          this.mainCategoryService.addMain_categories(main_category).then(data =&gt; {
              console.log(data);
          })
      }
  }
  </code></pre>
  
  <p><strong>html</strong> </p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;div class="container-fluid"&gt;
      &lt;h2&gt;Add main category&lt;/h2&gt;
      &lt;form [formGroup]="addMCform"&gt;
          &lt;div class="form-group"&gt;
              &lt;label&gt;Name of main category&lt;/label&gt;
              &lt;input [class.is-invalid]="name.invalid &amp;&amp; name.touched" formControlName="name" type="text"
                  class="form-control" placeholder="Enter name of category"&gt;
              &lt;div *ngIf="name.invalid &amp;&amp; name.touched"&gt;
                  &lt;small *ngIf="name.errors?.required" class="text-danger"&gt; name is required&lt;/small&gt;
                  &lt;small *ngIf="name.errors?.minlength" class="text-danger"&gt; name must be at least 3 characters &lt;/small&gt;
              &lt;/div&gt;
          &lt;/div&gt;
          &lt;div class="form-group"&gt;
              &lt;label&gt;Description:&lt;/label&gt;
              &lt;textarea class="form-control" rows="5" input type="textarea" formControlName="description"
                  placeholder="Enter description"&gt;&lt;/textarea&gt;
          &lt;/div&gt;
          &lt;button type="button" class="btn btn-primary" (click)="addMain_categories()"&gt;Add main category&lt;/button&gt;
      &lt;/form&gt;
  &lt;/div&gt;
  </code></pre>