In Kotlin How Can I Convert an Int? to an Int

The direct answer, use the !! operator to assert that you trust a value is NOT null and therefore changing its type to the non null equivalent. A simple sample showing the assertion allowing the conversion (which applies to any nullable type, not just Int?)

val nullableInt: Int? = 1
val nonNullableInt: Int = nullableInt!! // asserting and smart cast

Another way to convert a value is via a null check. Not useful in your code above, but in other code (see Checking for null in conditions):

val nullableInt: Int? = 1
if (nullableInt != null) {
   // allowed if nullableInt could not have changed since the null check
   val nonNullableInt: Int = nullableInt
}

This questions is also answered by the idiomatic treatment of nullability question: In Kotlin, what is the idiomatic way to deal with nullable values, referencing or converting them