title: Woocommerce Login: If user account does not exist, display error
body: <p>Currently when a user attempts to login with an email/username which does not exist, this default woocommerce error is displayed:</p>
  
  <p><a href="https://i.stack.imgur.com/NxS3E.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NxS3E.jpg" alt="enter image description here"></a></p>
  
  <p>I am trying check: <strong>If email/username DOES NOT exist, display different message</strong>.</p>
  
  <p>e.g. <em>"No account exists with this email, please create one."</em></p>
  
  <p>The hook <code>woocommerce_registration_error_email_exists</code> checks if a user tried to register with an email which already exists, so I am trying to reverse this with <code>!email_exists</code> - Can this be applied to the login field? </p>
  
  <p>My code below is not triggering and still displays the default message:</p>
  
  <pre><code>add_filter( 'woocommerce_registration_error_email_exists', 'no_account_found' );
  
  function no_account_found($email, $username = '', $password = '' ){
  
    if ( !email_exists( $email ) ) {
              return new WP_Error( 'registration-error-email-exists', apply_filters( 'woocommerce_registration_error_email_exists', __( 'No account found with this email. Please create one.', 'woocommerce' ), $email ) );
          }
  }
  </code></pre>