https://proandroiddev.com/one-liner-intent-bundle-extras-extractor-in-kotlin-f4b614b390c4

_Activity_LazyExtra.kt

inline fun <reified T: Any> Activity.extra(key: String, default: T? = null) = lazy {
    val value = intent?.extras?.get(key)
    if (value is T) value else default
}
inline fun <reified T: Any> Activity.extraNotNull(key: String, default: T? = null) = lazy {
    val value = intent?.extras?.get(key)
    requireNotNull(if (value is T) value else default) { key }
}