how to slove this error HTTP ERROR 500

<?php

// Upload configs.
define('UPLOAD_DIR', 'uploads',);
define('UPLOAD_MAX_FILE_SIZE', 10485760); // 10MB.
//@changed_2018-02-17_14.28
define('UPLOAD_ALLOWED_MIME_TYPES', 'image/jpeg,image/png,image/gif');
// Db configs.
define('HOST', '127.0.0.1');
define('DATABASE', 'krishnasweets_shop');
define('USERNAME', 'krishnasweets_shop');
define('PASSWORD', 'kxv7aKVUg0');
define('CHARSET', 'utf8');

/*
 * Enable internal report functions. This enables the exception handling, 
 * e.g. mysqli will not throw PHP warnings anymore, but mysqli exceptions 
 * (mysqli_sql_exception).
 * 
 * MYSQLI_REPORT_ERROR: Report errors from mysqli function calls.
 * MYSQLI_REPORT_STRICT: Throw a mysqli_sql_exception for errors instead of warnings. 
 * 
 * @link http://php.net/manual/en/class.mysqli-driver.php
 * @link http://php.net/manual/en/mysqli-driver.report-mode.php
 * @link http://php.net/manual/en/mysqli.constants.php
 */
$mysqliDriver = new mysqli_driver();
$mysqliDriver->report_mode = (MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);

/*
 * Create a new db connection.
 * 
 * @see http://php.net/manual/en/mysqli.construct.php
 */
$connection = new mysqli(HOST, USERNAME, PASSWORD, DATABASE);

$productSaved = FALSE;

if (isset($_POST['submit'])) {
    /*
     * Read posted values.
     */
    $productName = isset($_POST['title']) ? $_POST['title'] : '';
    $productSpecification = isset($_POST['specification']) ? $_POST['specification'] : '';
    $productCategory = isset($_POST['menu_id']) ? $_POST['menu_id'] : '';
    $productPrice = isset($_POST['price']) ? $_POST['price'] :'';
    $productDescription = isset($_POST['description']) ? $_POST['description'] : '';
    /*
     * Validate posted values.
     */
    if (empty($productName)) {
        $errors[] = 'Please provide a product name.';
    }

    if ($productPrice == 0) {
        $errors[] = 'Please provide the quantity.';
    }

    if (empty($productDescription)) {
        $errors[] = 'Please provide a description.';
    }
    if (empty($productSpecification)) {
        $errors[] = 'Please provide a Specification.';
    }
    if (empty($productCategory)) {
        $errors[] = 'Please provide a Category.';
    }
    
    /*
     * Create "uploads" directory if it doesn't exist.
     */
    if (!is_dir(UPLOAD_DIR)) {
        mkdir(UPLOAD_DIR, 0777, true);
    }

    /*
     * List of file names to be filled in by the upload script 
     * below and to be saved in the db table "products_images" afterwards.
     */
    $filenamesToSave = [];

    $allowedMimeTypes = explode(',', UPLOAD_ALLOWED_MIME_TYPES);

    /*
     * Upload files.
     */
    if (!empty($_FILES)) {
        if (isset($_FILES['file']['error'])) {
            foreach ($_FILES['file']['error'] as $uploadedFileKey => $uploadedFileError) {
                if ($uploadedFileError === UPLOAD_ERR_NO_FILE) {
                    $errors[] = 'You did not provide any files.';
                } elseif ($uploadedFileError === UPLOAD_ERR_OK) {
                    $uploadedFileName = basename($_FILES['file']['name'][$uploadedFileKey]);

                    if ($_FILES['file']['size'][$uploadedFileKey] <= UPLOAD_MAX_FILE_SIZE) {
                        $uploadedFileType = $_FILES['file']['type'][$uploadedFileKey];
                        $uploadedFileTempName = $_FILES['file']['tmp_name'][$uploadedFileKey];

                        $uploadedFilePath = rtrim(UPLOAD_DIR, '/') . '/' . $uploadedFileName;

                        if (in_array($uploadedFileType, $allowedMimeTypes)) {
                            if (!move_uploaded_file($uploadedFileTempName, $uploadedFilePath)) {
                                $errors[] = 'The file "' . $uploadedFileName . '" could not be uploaded.';
                            } else {
                                $filenamesToSave[] = $uploadedFilePath;
                            }
                        } else {
                            $errors[] = 'The extension of the file "' . $uploadedFileName . '" is not valid. Allowed extensions: JPG, JPEG, PNG, or GIF.';
                        }
                    } else {
                        $errors[] = 'The size of the file "' . $uploadedFileName . '" must be of max. ' . (UPLOAD_MAX_FILE_SIZE / 1024) . ' KB';
                    }
                }
            }
        }
    }

    /*
     * Save product and images.
     */
    if (!isset($errors)) {
        /*
         * The SQL statement to be prepared. Notice the so-called markers, 
         * e.g. the "?" signs. They will be replaced later with the 
         * corresponding values when using mysqli_stmt::bind_param.
         * 
         * @link http://php.net/manual/en/mysqli.prepare.php
         */
        $sql = 'INSERT INTO products (
                    title,
                    price,
                    specification,
                    menu_id,
                    description
                ) VALUES (
                    ?, ?, ?, ?, ?
                )';

        /*
         * Prepare the SQL statement for execution - ONLY ONCE.
         * 
         * @link http://php.net/manual/en/mysqli.prepare.php
         */
        $statement = $connection->prepare($sql);

        /*
         * Bind variables for the parameter markers (?) in the 
         * SQL statement that was passed to prepare(). The first 
         * argument of bind_param() is a string that contains one 
         * or more characters which specify the types for the 
         * corresponding bind variables.
         * 
         * @link http://php.net/manual/en/mysqli-stmt.bind-param.php
         */
        $statement->bind_param('sssss',  $productName, $productPrice,  
            $productSpecification, $productCategory,$productDescription);

        /*
         * Execute the prepared SQL statement.
         * When executed any parameter markers which exist will 
         * automatically be replaced with the appropriate data.
         * 
         * @link http://php.net/manual/en/mysqli-stmt.execute.php
         */
        $statement->execute();

        // Read the id of the inserted product.
        $lastInsertId = $connection->insert_id;

        /*
         * Close the prepared statement. It also deallocates the statement handle.
         * If the statement has pending or unread results, it cancels them 
         * so that the next query can be executed.
         * 
         * @link http://php.net/manual/en/mysqli-stmt.close.php
         */
        $statement->close();
if(!$statement)
{
  echo mysqli_error($statement);
}
        /*
         * Save a record for each uploaded file.
         */
        foreach ($filenamesToSave as $filename) {
            $sql = 'INSERT INTO products_images (
                        product_id,
                        filename
                    ) VALUES (
                        ?, ?
                    )';

            $statement = $connection->prepare($sql);

            $statement->bind_param('is', $lastInsertId, $filename);

            $statement->execute();

            $statement->close();
        }

        /*
         * Close the previously opened database connection.
         * 
         * @link http://php.net/manual/en/mysqli.close.php
         */
        $connection->close();
         if($connection)
        {
            header('Location: addproduct.php?success=true');
        }
        
        $productSaved = TRUE;

        /*
         * Reset the posted values, so that the default ones are now showed in the form.
         * See the "value" attribute of each html input.
         */
        $productName = $productPrice = $productDescription = NULL;
    }
}
?>