title: validation service isssue in formcontrol default value as null
body: <p>Am using Angular 10 ..Password validator Service</p>
  <pre><code> static password(control: AbstractControl) {
  
          // {6,100}           - Assert password is between 6 and 100 characters
          // (?=.*[0-9])       - Assert a string has at least one number
          if (control.value.match(/^(?=.*[0-9])[a-zA-Z0-9!@#$%^&amp;*]{6,100}$/)) {
            return null;
          } else {
            return { invalidPassword: true };
          }
        }
  </code></pre>
  <p><strong>Working Code</strong></p>
  <pre><code>this.loginForm = this.formBuilder.group({
        username:'' ,
        password: ['', [ValidationService.password]]
      });
  </code></pre>
  <p><strong>Not working Code :</strong></p>
  <pre><code>  this.loginForm = this.formBuilder.group({
            username:'' ,
            password: [null, [ValidationService.password]]
          });
  </code></pre>
  <p>I Have used null...But now getting below error while loading login form</p>
  <p>How to fix that ..Please let me know</p>
  <p><a href="https://i.stack.imgur.com/9BHcH.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/9BHcH.png" alt="enter image description here" /></a></p>
  <p>EDIT :</p>
  <p><strong>HTML</strong></p>
  <pre><code>          &lt;div class=&quot;input-group mb-4&quot;&gt;
              &lt;div class=&quot;input-group-prepend&quot;&gt;
                &lt;span class=&quot;input-group-text&quot;&gt;&lt;i class=&quot;icon-lock&quot;&gt;&lt;/i&gt;&lt;/span&gt;
              &lt;/div&gt;
              &lt;input type=&quot;password&quot; class=&quot;form-control&quot; placeholder=&quot;Password&quot; autocomplete=&quot;current-password&quot;
                formControlName=&quot;password&quot; required&gt;
            &lt;/div&gt;
            &lt;div class=&quot;form-group row&quot;&gt;
              &lt;div class=&quot;col-md-9&quot;&gt;
             
                &lt;ar-validation-message [control]=&quot;loginForm.controls.password&quot;&gt;&lt;/ar-validation-message&gt;
              &lt;/div&gt;
            &lt;/div&gt;
  </code></pre>