go vet caught the test's Mount call missing the trailing []byte
streamSecret arg added by the UPnP slice's Task 2. The test passed nil
for *playlists.Scheduler but didn't pass anything for []byte, so the
arg count was one short.
Added nil for the streamSecret position - the test exercises route
registration only, not the cast-token endpoint, so the secret value
doesn't matter for what this test asserts.
bvandeusen
9e67088fdb