Shaun_Max
addEventListener( type:String, ...
FeathersEventType.TRANSITION_IN_COMPLETE is a String
It demands String, you've passed String, IDE can't figure out that your string will never be used as an event type.
It's more of a Starling / EcmaScript approach not to throw errors when event type is unregistered / not to register event types, but I assume it would be hard to do that kind of checks as you can add new event types at runtime with dispatchEventWith( myStringType, ...