Hi folks, just wondering why this code throws

NoSuchElementException

. Does not null count as a produced value?

suspend fun main(args: Array<String>) {
    val someThingNullable: Any? = null
    val result = mono { someThingNullable }.awaitSingle()
    println(result)
}

Thanks in advance for any answer !

https://kotlinlang.org/api/kotlinx.coroutines/kotlinx-coroutines-reactor/kotlinx.coroutines.reactor/mono.html

null

does not count as a value. Also, reactive streams in general don't permit passing

null

values through them.

Oh mb i missed that part in docs. Thanks for the help !!

you can use

.awaitSingleOrNull()

if you want to handle an empty mono as well. Keep in mind that there's a functional difference between a Mono that succeeds without emitting a value, and a Mono emitting a

null

value. But in this case you're using the

mono

function, which does not emit a value if the code block produces a

null

value, but succeeds directly.