knows how to deal with each of them.

``error_handler`` (default::class:`Symfony\\Component\\Runtime\\Internal\\BasicErrorHandler` or:class:`Symfony\\Component\\Runtime\\Internal\\SymfonyErrorHandler` for ``SymfonyRuntime``)

Defines the class to use to handle PHP errors.

``env_var_name`` (default: ``"APP_ENV"``)

To define the name of the env var for the Symfony env.

``debug_var_name`` (default: ``"APP_DEBUG"``)

To define the name of the debug var for the debug flag.

..versionadded::5.4

The ``env_var_name`` and ``debug_var_name`` options was introduced in Symfony 5.4.

Create Your Own Runtime