The Functions Framework contract specifies defaults for:

• FUNCTION_TARGET=function
• FUNCTION_SIGNATURE_TYPE=http

https://github.com/GoogleCloudPlatform/functions-framework#parameters

Expected

The PHP FF should use these defaults if env vars aren't provided. There should be no fatal errors when omitting these configs.

Actual

router.php on line 53 throws a PHP Fatal error: Uncaught RuntimeException.