Как исправить ошибку Can't create handler inside thread that has not called Looper.prepare() на Kotlin?

class ShowTariffsActivity : AppCompatActivity() {
 
    var tariffList : ArrayList<WebSocketResponse> = arrayListOf()
 
    var adapter: TarrifsAdapter? = null
 
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_show_tariffs)
 
        val departureId = intent.getIntExtra("id", 0)
 
        val client = OkHttpClient.Builder()
            .readTimeout(3, TimeUnit.SECONDS)
            .build()
        val request = Request.Builder()
            .url("ws://68.183.30.45/ws/calculation/${departureId}/")
            .build()
        val wsListener = WebSocketList()
        val webSocket = client.newWebSocket(request, wsListener)
 
        rcViewTarrif.hasFixedSize()
        rcViewTarrif.layoutManager = LinearLayoutManager(this)
        adapter = TarrifsAdapter(tariffList, this)
        rcViewTarrif.adapter = adapter
    }
 
    private class WebSocketList: WebSocketListener() {
        override fun onMessage(webSocket: WebSocket, text: String) {
            val tarrifs = ShowTariffsActivity()
            val result = Klaxon().parse<WebSocketResponse>(text)
 
            if (result != null) {
                tarrifs.tariffList.add(result)
            }
 
        }
 
        override fun onClosing(webSocket: WebSocket, code: Int, reason: String) {
            webSocket.close(NORMAL_CLOSURE_STATUS, null)
        }
 
        override fun onFailure(webSocket: WebSocket, t: Throwable, response: Response?) {
            Log.d("WebSocket", t.message.toString())
        }
 
        companion object {
            private val NORMAL_CLOSURE_STATUS = 1000
        }
    }
}

override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_show_tariffs)
 
        val departureId = intent.getIntExtra("id", 0)
 
        Handler(Looper.getMainLooper()).post {
            testWSS(departureId)
        }
 
        rcViewTarrif.hasFixedSize()
        rcViewTarrif.layoutManager = LinearLayoutManager(this)
        adapter = TarrifsAdapter(tariffList, this)
        rcViewTarrif.adapter = adapter
    }
 
    private fun testWSS(id: Int) {
        val ws = WebSocketFactory().createSocket("ws://68.183.30.45/ws/calculation/$id/", 5000)
 
        ws.addListener(object : WebSocketAdapter() {
            override fun onTextMessage(websocket: WebSocket?, text: String?) {
                super.onTextMessage(websocket, text)
 
                val result = Klaxon().parse<WebSocketResponse>(text!!)
                tariffList.add(result!!)
            }
 
            override fun onTextMessageError(websocket: WebSocket?, cause: WebSocketException?, data: ByteArray?) {
                super.onTextMessageError(websocket, cause, data)
                Log.d("WebSocket", cause?.message.toString())
            }
 
            override fun onCloseFrame(websocket: WebSocket?, frame: WebSocketFrame?) {
                super.onCloseFrame(websocket, frame)
                Log.v("WSS", "closing socket")
            }
        })
    }