Showing 'TypeError: Failed to fetch' while creating contact form for my charity

I'm getting the message while creating contact form for my website.The Follwing error is showing !

Here is the HTML code for contact form in index.html -

<div class="col-lg-6">
        <form action="forms/contact.php" method="post" class="php-email-form">
          <div class="row gy-4">

            <div class="col-md-6">
              <input type="text" name="name" class="form-control" placeholder="Your Name" required>
            </div>

            <div class="col-md-6 ">
              <input type="email" class="form-control" name="email" placeholder="Your Email" required>
            </div>

            <div class="col-md-12">
              <input type="text" class="form-control" name="subject" placeholder="Subject" required>
            </div>

            <div class="col-md-12">
              <textarea class="form-control" name="message" rows="6" placeholder="Message" required></textarea>
            </div>

            <div class="col-md-12 text-center">
              <div class="loading">Loading</div>
              <div class="error-message"></div>
              <div class="sent-message">Your message has been sent. Thank you!</div>

              <button type="submit">Send Message</button>
            </div>

          </div>
        </form>

      </div>

Next here is the code for contact.php -

     <?php
  
  $receiving_email_address = 'arkajyotichakraborty99@gmail.com';

  if( file_exists($php_email_form = '../assets/vendor/php-email-form/php-email-form.php' )) {
    include( $php_email_form );
  } else {
    die( 'Unable to load the "PHP Email Form" Library!');
  }

  $contact = new PHP_Email_Form;
  $contact->ajax = true;
  
  $contact->to = $receiving_email_address;
  $contact->from_name = $_POST['name'];
  $contact->from_email = $_POST['email'];
  $contact->subject = $_POST['subject'];

  

  $contact->add_message( $_POST['name'], 'From');
  $contact->add_message( $_POST['email'], 'Email');
  $contact->add_message( $_POST['message'], 'Message', 10);

  echo $contact->send();
?>

Please help me to solve this problem. A big Thank you in advance :)