InMemorySessionStorage fails with exception if the session id is invalid

[audax]

The contract of the interface of session storages defines that SessiosStorage.lookup should only call the consumer if the session can be found and otherwise fail silently.

The InMemorySessionStorage throws an IllegalArgumentException is the session can not be found and thus crashes the pipeline.

https://github.com/Kotlin/ktor/blob/master/ktor-features/ktor-server-sessions/src/org/jetbrains/ktor/sessions/SessionStorage.kt#L46

private class InMemorySessionStorage : SessionStorage {
    private val sessions = ConcurrentHashMap<String, ByteArray>()

    override fun save(id: String, contentProvider: (OutputStream) -> Unit): Future<Unit> {
        val baos = ByteArrayOutputStream()
        contentProvider(baos)
        sessions[id] = baos.toByteArray()
        return CompletableFuture.completedFuture(Unit)
    }

    override fun <R> read(id: String, consumer: (InputStream) -> R): Future<R> = CompletableFuture<R>().apply {
        sessions[id]?.let { bytes -> complete(consumer(bytes.inputStream())) } ?: throw IllegalArgumentException("Session $id not found")
    }

    override fun invalidate(id: String): Future<Unit> {
        sessions.remove(id)
        return CompletableFuture.completedFuture(Unit)
    }
}

Here is a minimal test that that shows how this behavior crashes the pipeline:
https://gist.github.com/audax/ac07afbe225d0d6a04f57a9fa492bffb