I’m traveling so I’m a bit late in seeing this, but switch router.handle —> router.fetch should fix
I’m traveling so I’m a bit late in seeing this, but switch router.handle —> router.fetch should fix your issue. “handle” was finally deprecated fully in v5 
When you access router.handle now, it’s trying to register a route on the HANDLE verb instead of processing a request… so it fails to respond.
When you access router.handle now, it’s trying to register a route on the HANDLE verb instead of processing a request… so it fails to respond.

