Must start with number, buffer, array or string, what's the problem?

Question

Node.js

When I run my bot, I get an error: I

'm using TypeScript, but when I try to run it in JS, I get the same error.
The code:

function reWebLogOn() {
    steamWebLogOn.webLogOn((sessionID, newCookie) => {
        getSteamAPIKey({
            sessionID: sessionID,
            webCookie: newCookie
        }, (err, APIKey) => {
            offers.setup({
                sessionID: sessionID,
                webCookie: newCookie,
                APIKey: APIKey
            });
        });
    });
}

client.on('loggedOn', function() {
    console.log("[BOT] Logged in trough Steam.");
    reWebLogOn();
});