title: angular material mat-radio-button default checked not working after adding name on mat-radio-group
body: <p>In an Angular 5 app with angular material 5.2.5, when using this code the radio button default checked is working but there is an error in console</p>
  
  <p>Code :</p>
  
  <pre><code>&lt;mat-radio-group [(ngModel)]="collection"&gt;
    &lt;mat-radio-button class="collectionRadioButton" 
     *ngFor="let coll of collections" 
     [value]="coll.endPoint" 
     [checked]="coll.isDefault" 
     (change)="clearResults()"&gt;
    {{coll.label}}
    &lt;/mat-radio-button&gt;
  &lt;/mat-radio-group&gt;
  </code></pre>
  
  <p>Error in Chrome console : </p>
  
  <pre><code>ERROR Error: If ngModel is used within a form tag, either the name attribute must be set or the form control must be defined as 'standalone' in ngModelOptions.
  
  Example 1: &lt;input [(ngModel)]="person.firstName" name="first"&gt;   
  Example 2: &lt;input [(ngModel)]="person.firstName" [ngModelOptions]="{standalone: true}"&gt;
  at Function.TemplateDrivenErrors.missingNameException (forms.js:5891)
  at NgModel._checkName (forms.js:6244)
  at NgModel._checkForErrors (forms.js:6217)
  at NgModel.ngOnChanges (forms.js:6099)
  at checkAndUpdateDirectiveInline (core.js:12407)
  at checkAndUpdateNodeInline (core.js:13935)
  at checkAndUpdateNode (core.js:13878)
  at debugCheckAndUpdateNode (core.js:14771)
  at debugCheckDirectivesFn (core.js:14712)
  </code></pre>
  
  <p>But when adding a name to mat-radio-group </p>
  
  <pre><code>&lt;mat-radio-group [(ngModel)]="collection" [name]="'aList'"&gt;
  </code></pre>
  
  <p>then the radio button list is still correctly generated but the default checked is no longer working ... </p>