That won't error in the way you'd expect.

An empty string will generate a `OpenTokArgumentException("Session ID is invalid")` without even making a REST call our servers.

`$foo = REPLACE_WITH_SESSION_ID` actually results in $foo have being set to "REPLACE_WITH_SESSION_ID" because PHP treats constants in a stupid way. Ultimately it will result in a `OpenTokArchiveException("Session ID is invalid")` or `OpenTokArchiveException("Session not found")` but exactly which I'm not sure.