Android Studio – Kotlin Edit Text as Integer

I want to make an app where you have to guess two numbers that eaquals a random number. But my app crash at the start because of java.lang.NumberFormatException: For input string: ""

val intNumber1 = etNumber1.text.toString().toInt() is the line that causes the crash. But I dont know what to do.

Here is my main activity:

//Buttons und Text initialisieren
private lateinit var btnCheck: Button
private lateinit var tvRndNumber: TextView
private lateinit var etNumber1: EditText
private lateinit var etNumber2: EditText



override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)



    //Buttons und Text verknüpfen
    btnCheck = findViewById(R.id.checkButton)
    tvRndNumber = findViewById(R.id.randomNumber)
    etNumber1 = findViewById(R.id.inputNumber1)
    etNumber2 = findViewById(R.id.inputNumber2)



    val intNumber1 = etNumber1.text.toString().toInt()
    val intNumber2 = etNumber2.text.toString().toInt()



    fun getRandomNumber(): Int {
        return Random.nextInt(0,100)
    }



    var intRdnNumber = getRandomNumber()
    tvRndNumber.text = intRdnNumber.toString()



    fun checkNumbers(num1: Int, num2: Int){

        if (num1 + num2 == intRdnNumber) {
            tvRndNumber.text = "Richtig"
        }
        else {
            Toast.makeText(this,"Probier es nochmal", Toast.LENGTH_LONG).show()
        }
    }



    btnCheck.setOnClickListener {
        checkNumbers(intNumber1, intNumber2)
    }