Enable dispatchEvent function in my custom class

class Model {
    constructor( initObj ){
        this.eventer = new EventTarget();
        this.dispatchEvent = this.eventer.dispatchEvent

    }
    run(){
        // works
        this.eventer.dispatchEvent( new CustomEvent('sessionEvent', { detail:1 } ) )

        // Uncaught (in promise) TypeError: Illegal invocation
        this.dispatchEvent( new CustomEvent('sessionEvent', { detail:1 } ) )
    }

}

OR

What is the best way to enable dispatchEvent functionality in my class? Ideally to use it like so:

model.addEventListener('someEvent' , onSomeEvent )