Why does ajax return empty string from php json_encode

I'm trying to return json_encode to an ajax function through php.

The echo json_encode($eMessage) function outputs this to the screen if I point the form target to the php file : php output to screen

But the ajax function returns this : ajax function output

Here's my code :

PHP in sendEmail.php :

<?php
    require 'aws/aws-autoloader.php';

    use Aws\Ses\SesClient;
    use Aws\Exception\AwsException;
    use Aws\Credentials\CredentialProvider;
    
    $profile = 'default';
    $path = 'aws/credentials';
    $provider = CredentialProvider::ini($profile, $path); 
    $provider = CredentialProvider::memoize($provider);
    $eMessage = [];
    $SesClient = new SesClient([
        'credentials' => $provider,
        'version' => '2010-12-01',
        'region'  => 'eu-north-1',
    ]);

    if($_SERVER['REQUEST_METHOD'] == "GET") {
        if(isset($_REQUEST['email']) && isset($_REQUEST['name']) && isset($_REQUEST['subject']) && isset($_REQUEST['message'])) {

            $from = $_REQUEST['email'];
            $name = $_REQUEST['name'];
            $topic = $_REQUEST['topic'];
            $message = $_REQUEST['message'];

            // Replace sender@example.com with your "From" address.
            // This address must be verified with Amazon SES.
            $sender_email = 'senderEmail@gmail.com';

            // Replace these sample addresses with the addresses of your recipients. If
            // your account is still in the sandbox, these addresses must be verified.
            $recipient_emails = ['recipientEmail@outlook.com'];

            // Specify a configuration set. If you do not want to use a configuration
            // set, comment the following variable, and the
            // 'ConfigurationSetName' => $configuration_set argument below.
            $configuration_set = 'configset';

            $subject = 'Email From ' .$name. ' at ' . $from;
            $plaintext_body = 'This email was sent with Amazon SS using the AWS SDK for PHP.' ;
            $html_body =  '<h1>'.$topic.'</h1>'.
                        '<p>'.$message.'</p>';
            $char_set = 'UTF-8';

            try {
                $result = $SesClient->sendEmail([
                    'Destination' => [
                        'ToAddresses' => $recipient_emails,
                    ],
                    'ReplyToAddresses' => [$sender_email],
                    'Source' => $sender_email,
                    'Message' => [
                    'Body' => [
                        'Html' => [
                            'Charset' => $char_set,
                            'Data' => $html_body,
                        ],
                        'Text' => [
                            'Charset' => $char_set,
                            'Data' => $plaintext_body,
                        ],
                    ],
                    'Subject' => [
                        'Charset' => $char_set,
                        'Data' => $subject,
                    ],
                    ],
                    // If you aren't using a configuration set, comment or delete the
                    // following line
                    'ConfigurationSetName' => $configuration_set,
                ]);
                $eMessage ['Success'] = "Email sent!";
                $messageId = $result['MessageId'];
                echo("Email sent! Message ID: $messageId"."\n");
                } catch (AwsException $e) {
                    // output error message if fails
                    echo $e->getMessage();
                    $eMessage ['Failed'] = "GWGWGWJR";
                    
                };
                echo json_encode($eMessage);

        };

    }


?>

I had to add this if check if(isset($_REQUEST['email']) && isset($_REQUEST['name']) && isset($_REQUEST['subject']) && isset($_REQUEST['message'])) to remove this error : Undefined array key

AJAX in app.js: ajax function

    $(document).delegate("#mybtn", "click", function() {

        $.ajax({
            type: "GET",
            url: 'sendMail.php', 
            success: function (response) {
            console.log(response)
            }
        });

    });

Please can someone help me with this.

I also tried the javascript fetch function : javascript fetch function

    const form = document.querySelector('form')
    form.addEventListener('submit', event => {
      // prevent the form submit from refreshing the page
      // event.preventDefault()

      fetch('sendMail.php', {
        method: 'GET',
        headers: {
          'Accept': 'application/json',
        },
      })
      .then(response => response.json())
      .then(data => console.log(data));

Which returned this output : first error message And if I comment out the .then(response => response.json()) line, it returns this output : second error message

source https://stackoverflow.com/questions/77298081/why-does-ajax-return-empty-string-from-php-json-encode