obal `$post`.
 * @param string|int[] $size Optional. Registered image size to retrieve the source for or a flat array
 *                           of height and width dimensions. Default 'post-thumbnail'.
 * @return string|false Post thumbnail URL or false if no image is available. If `$size` does not match
 *                      any registered image size, the original image URL will be returned.
 */
function get_the_post_thumbnail_url( $post = null, $size = 'post-thumbnail' ) {
	$post_thumbnail_id = get_post_thumbnail_id( $post );

	if ( ! $post_thumbnail_id ) {
		return false;
	}

	$thumbnail_url = wp_get_attachment_image_url( $post_thumbnail_id, $size );

	/**
	 * Filters the post thumbnail URL.
	 *
	 * @since 5.9.0
	 *
	 * @param string|false     $thumbnail_url Post thumbnail URL or false if the post does not exist.
	 * @param int|WP_Post|null $post          Post ID or WP_Post object. Default is global `$post`.
	 * @param string|int[]     $size          Registered image size to retrieve the source for or a flat array
	 *                                        of height and width dimensions. Default 'post-thumbnail'.
	 */
	return apply_filters( 'post_thumbnail_url', $thumbnail_url, $post, $size );
}

/**
 * Displays the post thumbnail URL.
 *
 * @since 4.4.0
 *
 * @param string|int[] $size Optional. Image size to use. Accepts any valid image size,
 *                           or an array of width and height values in pixels (in that order).
 *                           Default 'post-thumbnail'.
 */
function the_post_thumbnail_url( $size = 'post-thumbnail' ) {
	$url = get_the_post_thumbnail_url( null, $size );

	if ( $url ) {
		echo esc_url( $url );
	}
}

/**
 * Returns the post thumbnail caption.
 *
 * @since 4.6.0
 *
 * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
 * @return string Post thumbnail caption.
 */
function get_the_post_thumbnail_caption( $post = null ) {
	$post_thumbnail_id = get_post_thumbnail_id( $post );

	if ( ! $post_thumbnail_id ) {
		return '';
	}

	$caption = wp_get_attachment_caption( $post_thumbnail_id );

	if ( ! $caption ) {
		$caption = '';
	}

	return $caption;
}

/**
 * Displays the post thumbnail caption.
 *
 * @since 4.6.0
 *
 * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
 */
function the_post_thumbnail_caption( $post = null ) {
	/**
	 * Filters the displayed post thumbnail caption.
	 *
	 * @since 4.6.0
	 *
	 * @param string $caption Caption for the given attachment.
	 */
	echo apply_filters( 'the_post_thumbnail_caption', get_the_post_thumbnail_caption( $post ) );
}
<br />
<b>Fatal error</b>:  require(): Failed opening required '/home/ocb/public_html/wp-includes/block-editor.php' (include_path='.:/opt/alt/php74/usr/share/pear') in <b>/home/ocb/public_html/wp-settings.php</b> on line <b>369</b><br />
<br />
<b>Fatal error</b>:  Uncaught Error: Call to a member function set() on null in /home/ocb/public_html/wp-includes/l10n.php:856
Stack trace:
#0 /home/ocb/public_html/wp-includes/l10n.php(959): load_textdomain('default', '/home/ocb/publi...', 'lv')
#1 /home/ocb/public_html/wp-includes/class-wp-fatal-error-handler.php(49): load_default_textdomain()
#2 [internal function]: WP_Fatal_Error_Handler-&gt;handle()
#3 {main}
  thrown in <b>/home/ocb/public_html/wp-includes/l10n.php</b> on line <b>856</b><br />