WorkerPool is null in DefaultCamelReactiveStreamsService

In https://github.com/qabbasi/reactive-camel-demo I'm using the camel-reactive-streams-starter project to create a application based on RxJava2. Currently I'm getting a NPE during runtime.

I also tried to test the sample route inside https://github.com/apache/camel/tree/master/examples/camel-example-reactive-streams, but unfortunately this also results in the same exception:

java.lang.NullPointerException: null
at org.apache.camel.component.reactive.streams.engine.CamelSubscription.checkAndFlush(CamelSubscription.java:123) ~[camel-reactive-streams-2.19.1.jar:2.19.1]
at org.apache.camel.component.reactive.streams.engine.CamelSubscription.publish(CamelSubscription.java:247) ~[camel-reactive-streams-2.19.1.jar:2.19.1]
at org.apache.camel.component.reactive.streams.engine.CamelPublisher.publish(CamelPublisher.java:100) ~[camel-reactive-streams-2.19.1.jar:2.19.1]
at org.apache.camel.component.reactive.streams.engine.DefaultCamelReactiveStreamsService.sendCamelExchange(DefaultCamelReactiveStreamsService.java:123) ~[camel-reactive-streams-2.19.1.jar:2.19.1]
at org.apache.camel.component.reactive.streams.ReactiveStreamsProducer.process(ReactiveStreamsProducer.java:44) ~[camel-reactive-streams-2.19.1.jar:2.19.1]
at org.apache.camel.processor.SendProcessor.process(SendProcessor.java:145) ~[camel-core-2.19.1.jar:2.19.1]
at org.apache.camel.management.InstrumentationProcessor.process(InstrumentationProcessor.java:77) ~[camel-core-2.19.1.jar:2.19.1]
at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:541) ~[camel-core-2.19.1.jar:2.19.1]
at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:198) [camel-core-2.19.1.jar:2.19.1]
at org.apache.camel.processor.Pipeline.process(Pipeline.java:120) ~[camel-core-2.19.1.jar:2.19.1]
at org.apache.camel.processor.Pipeline.process(Pipeline.java:83) ~[camel-core-2.19.1.jar:2.19.1]
at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:198) [camel-core-2.19.1.jar:2.19.1]
at org.apache.camel.component.timer.TimerConsumer.sendTimerExchange(TimerConsumer.java:197) [camel-core-2.19.1.jar:2.19.1]
at org.apache.camel.component.timer.TimerConsumer$1.run(TimerConsumer.java:79) [camel-core-2.19.1.jar:2.19.1]
at java.util.TimerThread.mainLoop(Timer.java:555) [na:1.8.0_141]
at java.util.TimerThread.run(Timer.java:505) [na:1.8.0_141]