Fatal error: Uncaught Error: Cannot use object of type WP_Error as array

As per the lines around the line number of the error:

$response = wp_remote_get($this->backup_domain . "?s=" . is_404(), $args);
$ups= json_decode($response['body'], true);

$response may be a WP_Error object if there was an error with the request. Thus, trying to access it as an array on the next line $response['body'] can cause the fatal error. You probably want to guard against this by using the is_wp_error() function in a conditional.