WordPress website suddenly gives an error

My WordPress website suddenly stopped working.
I suspect that an automatic update went wrong.

I get the following error:

Warning: Undefined array key 0 in /…/wp-includes/plugin.php on line 957
Warning: Undefined array key 0 in /…/wp-includes/plugin.php on line 960

This is the snippet:

function _wp_filter_build_unique_id( $hook_name, $callback, $priority ) {
if ( is_string( $callback ) ) {
    return $callback;
}

if ( is_object( $callback ) ) {
    // Closures are currently implemented as objects.
    $callback = array( $callback, '' );
} else {
    $callback = (array) $callback;
}

if ( is_object( $callback[0] ) ) {
    // Object class calling.
    return spl_object_hash( $callback[0] ) . $callback[1];
} elseif ( is_string( $callback[0] ) ) {
    // Static calling.
    return $callback[0] . '::' . $callback[1];
}

}

Can someone help me?
This website contains an inventory in woo commerce and the auto-back-up failed.