src/Errors.php
public function getReservedCodes()
    {
        $reserved = [];

        /** @var ErrorFactoryInterface|string $factory */
        foreach ($this->factories as $factoryClass => $factory) {
            $reserved[$factoryClass] = $factory->getReservedDiapason();
        }

        return $reserved;
    }
public function getReservedCodes()
    {
        $reserved = [];

        /** @var ErrorFactoryInterface|string $factory */
        foreach ($this->factories as $factoryClass => $factory) {
            $reserved[$factoryClass] = $factory->getReservedDiapason();
        }

        return $reserved;
    }
Get reserved codes

@return array