Expected argument of type object, but instead had type object

Question

I'm using map from 'core-js/feature/map'. By calling has on the map I get an Error as follows:

ERROR: org.mozilla.javascript.EcmaError: TypeError: Expected argument of type object, but instead had type object

The error is thrown in line 16 (if (this.playerStateMap.has(user)) {) of

var RoulettePlayerManager = /** @class */ (function () {
    function RoulettePlayerManager(gameManager) {
        this.gameManager = gameManager;
        this.playerStateMap = new Map();
    }
    RoulettePlayerManager.prototype.placeBet = function (user, data) {
        var buyIn = data;
        var betSum = buyIn.betAmountPurple + buyIn.betAmountGreen + buyIn.betAmountBlue + buyIn.betAmountYellow;
        if (1 <= betSum &&
            betSum <=
                user
                    .getKnuddelAccount()
                    .getKnuddelAmount()
                    .asNumber()) {
            user.getKnuddelAccount().use(KnuddelAmount.fromKnuddel(betSum), BET_TEXT);
            if (this.playerStateMap.has(user)) {
                this.playerStateMap.set(user, new PlayerState_1.PlayerState(user, this.gameManager, data));
            }
            else {
                this.playerStateMap.get(user).updateBet(data);
            }
        }
    };
    return RoulettePlayerManager;
}());

The code is running in a java applications rhino engine.

I tried to import the full core-js lib but it didn't change anything.