Authentication bypass in Vartalap chat-server

Chat Server is the chat server for Vartalap, an open-source messaging application. Versions 2.3.2 until 2.6.0 suffer from a bug in validating the access token, resulting in authentication bypass. The function `this.authProvider.verifyAccessKey` is an async function, as the code is not using `await` to wait for the verification result. Every time the function responds back with success, along with an unhandled exception if the token is invalid. A patch is available in version 2.6.0.