angular 2 form validation giving undefined error message

I followed the angular 2 tutorial and tried to implement validation in a angular 2 form. See code:

<form #loginForm="ngForm" (ngSubmit)="login()">
    <div>
        <label for="email">Email:</label>
        <input type="text" id="email" name="email" required minlength="4" maxlength="24" [(ngModel)]="emailField" #name="ngModel" />
        <div *ngIf="email?.errors && (email?.dirty || email?.touched)" class="alert alert-danger">
            <div [hidden]="!email.errors.required">
              email is required
            </div>
            <div [hidden]="!email.errors.minlength">
              email must be at least 4 characters long.
            </div>
            <div [hidden]="!email.errors.maxlength">
              Name cannot be more than 24 characters long.
            </div>
        </div>
    </div>  
    <div>
        <label>Password:</label><input type="password" name="password" [(ngModel)]="passwordField" />
    </div>
    <div>
        <button [disabled]="!loginForm.form.valid" type="submit">Submit</button>
    </div>
</form>

The problem is that I am getting this error code :

ERROR Error: Uncaught (in promise): TypeError: Cannot read property 'errors' of undefined

I tried to implement it exactly as in the tutorial on the official site: https://angular.io/docs/ts/latest/cookbook/form-validation.html#!#template1