Currently any `currentUserLiteral` routes when accessed with a bad
token throw a 500 due to a SQL error that is raised because
`Model.findById` is invoked with `id={currentUserLiteral}`
(`id=me` in our case) when the url rewrite fails.
This commit changes the token middleware to return 401 Not Authorized
when the client is requesting a currentUserLiteral route without
a valid access token.
50e0e4808a