Hi, We're encountering an error using a HybridSource that is composed of a FileSource + KafkaSource, only when recovering from a savepoint [0]. This HybridSource is used to read from a Kafka topic's archives hosted on GCS via a bounded FileSource, and then automatically switch over to the data stream from the Kafka associated topic.
Has anyone seen this error before? [0] ``` 2022-05-03 09:47:57 org.apache.flink.util.FlinkException: Global failure triggered by OperatorCoordinator for 'Source: ShopAppTrackingEventUpdate_V1' (operator afb3208349a953c47059c1994f800aa2). at org.apache.flink.runtime.operators.coordination.OperatorCoordinatorHolder$LazyInitializedCoordinatorContext.failJob(OperatorCoordinatorHolder.java:545) at org.apache.flink.runtime.operators.coordination.RecreateOnResetOperatorCoordinator$QuiesceableContext.failJob(RecreateOnResetOperatorCoordinator.java:223) at org.apache.flink.runtime.source.coordinator.SourceCoordinatorContext.failJob(SourceCoordinatorContext.java:285) at org.apache.flink.runtime.source.coordinator.SourceCoordinator.lambda$runInEventLoop$8(SourceCoordinator.java:358) at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.base/java.lang.Thread.run(Unknown Source) Caused by: java.lang.NullPointerException: Source for index=0 not available at org.apache.flink.util.Preconditions.checkNotNull(Preconditions.java:104) at org.apache.flink.connector.base.source.hybrid.SwitchedSources.sourceOf(SwitchedSources.java:36) at org.apache.flink.connector.base.source.hybrid.HybridSourceSplitEnumerator.sendSwitchSourceEvent(HybridSourceSplitEnumerator.java:148) at org.apache.flink.connector.base.source.hybrid.HybridSourceSplitEnumerator.handleSourceEvent(HybridSourceSplitEnumerator.java:222) at org.apache.flink.runtime.source.coordinator.SourceCoordinator.lambda$handleEventFromOperator$1(SourceCoordinator.java:182) at org.apache.flink.runtime.source.coordinator.SourceCoordinator.lambda$runInEventLoop$8(SourceCoordinator.java:344) ... 3 more ```
