qmllint: Cannot 'qualify' access to private types like KeyEvent, MouseEvent.

It's currently not possible to make qmllint happy with statements like this (without qmllint disable):

    Keys.onEscapePressed: (event) => { 
        event.accepted = true;
    }

This is due to multiple issues when trying to compile the project:
1. It's not possible to annotate these types of functions. 'Keys.onEscapePressed: (event: KeyEvent) =>' results in this error:

error: Expected token `,'

2. Changing to Keys.onEscapePressed: function(event: KeyEvent) gives:

error: Type annotations are not permitted in function parameters in JavaScript functions

3. Moving the handler to a separate function like this gives another error:

    function handler(event: KeyEvent) : void {
        event.accepted = true;
    }
    Keys.onEscapePressed: handler

Could not compile function handler: Type QVariant of QVariant does not have a property accepted for writing

Or this if event is not used in the function:

Cannot resolve the argument type KeyEvent.

 So as of Qt 6.3.1 it's not possible to qualify this event handler.