javascript - Error: my website Form submission fails to send

one text

first of all my level is 0 in PHP and i'm learning to make websites.

my PHP Form doesn't work, when i press send message button this error pops out "Error: Form submission failed and no error message returned from: contact.php". I don't know what the problem is.

This is html form :

<form id="contact-form" action="contact.php" method="post" data-toggle="validator" role="form" class="php-email-form">
              <div class="row">
                <div class="col-md-6 form-group">
                  <input type="text" name="name" class="form-control" id="name" placeholder="Your Name" required>
                </div>
                <div class="col-md-6 form-group mt-3 mt-md-0">
                  <input type="email" class="form-control" name="email" id="email" placeholder="Your Email" required>
                </div>
              </div>
              <div class="form-group mt-3">
                <input type="text" class="form-control" name="subject" id="subject" placeholder="Subject" required>
              </div>
              <div class="form-group mt-3">
                <textarea class="form-control" name="message" rows="5" placeholder="Message" required></textarea>
              </div>
              <div class="my-3">
                <div class="loading">Loading</div>
                <div class="error-message"></div>
                <div class="sent-message">Your message has been sent. Thank you!</div>
              </div>
              
              <div class="text-center">
                <button id="submit" type="submit">Send Message</button>
              </div>
            </form>

This is contact.php

<?php
  $receiving_email_address = 'myemail@blabla.com';

  $to = 'myemail@blabla.com';
  $name = filter_input(INPUT_POST, 'name', FILTER_SANITIZE_SPECIAL_CHARS);
  $from = filter_input(INPUT_POST, 'email', FILTER_SANITIZE_EMAIL);
  $subject = filter_input(INPUT_POST, 'subject', FILTER_SANITIZE_SPECIAL_CHARS);
  $message = filter_input(INPUT_POST, 'message', FILTER_SANITIZE_SPECIAL_CHARS);

  if (filter_var($from, FILTER_VALIDATE_EMAIL)) {
    $headers = ['From' => ($name?"<$name> ":'').$from,
            'X-Mailer' => 'PHP/' . phpversion()
           ];

    mail($to, $subject, $message."\r\n\r\nfrom: ".$_SERVER['REMOTE_ADDR'], $headers);
    die('OK');
    
} else {
    die('Invalid address');
}

  echo $contact->send();
?>

this is my contact.js

(function () {
  "use strict";

  let forms = document.querySelectorAll('.php-email-form');

  forms.forEach( function(e) {
    e.addEventListener('submit', function(event) {
      event.preventDefault();

      let thisForm = this;

      let action = thisForm.getAttribute('action');
      let recaptcha = thisForm.getAttribute('data-recaptcha-site-key');
      
      if( ! action ) {
        displayError(thisForm, 'The form action property is not set!')
        return;
      }
      thisForm.querySelector('.loading').classList.add('d-block');
      thisForm.querySelector('.error-message').classList.remove('d-block');
      thisForm.querySelector('.sent-message').classList.remove('d-block');

      let formData = new FormData( thisForm );

      if ( recaptcha ) {
        if(typeof grecaptcha !== "undefined" ) {
          grecaptcha.ready(function() {
            try {
              grecaptcha.execute(recaptcha, {action: 'php_email_form_submit'})
              .then(token => {
                formData.set('recaptcha-response', token);
                php_email_form_submit(thisForm, action, formData);
              })
            } catch(error) {
              displayError(thisForm, error)
            }
          });
        } else {
          displayError(thisForm, 'The reCaptcha javascript API url is not loaded!')
        }
      } else {
        php_email_form_submit(thisForm, action, formData);
      }
    });
  });

  function php_email_form_submit(thisForm, action, formData) {
    fetch(action, {
      method: 'POST',
      body: formData,
      headers: {'X-Requested-With': 'XMLHttpRequest'}
    })
    .then(response => {
      return response.text();
    })
    .then(data => {
      thisForm.querySelector('.loading').classList.remove('d-block');
      if (data.trim() == 'OK') {
        thisForm.querySelector('.sent-message').classList.add('d-block');
        thisForm.reset(); 
      } else {
        throw new Error(data ? data : 'Form submission failed and no error message returned from: ' + action); 
      }
    })
    .catch((error) => {
      displayError(thisForm, error);
    });
  }

  function displayError(thisForm, error) {
    thisForm.querySelector('.loading').classList.remove('d-block');
    thisForm.querySelector('.error-message').innerHTML = error;
    thisForm.querySelector('.error-message').classList.add('d-block');
  }

})();