Use parent = contextJob instead of contextJob + UI
Use parent = contextJob instead of contextJob + UI

Since parent is `Job?`, change the type of `contextJob` to `Job?`
as well and remove `NonCancellable` as the null-object.
Kotlin/kotlinx.coroutines,Kotlin/kotlinx.coroutines,Kotlin/kotlinx.coroutines,Kotlin/kotlinx.coroutines,Kotlin/kotlinx.coroutines