fix: opencdc unwrap

[raulb]

Description

Follow up from #1343.

Using this OpenCDC processor, I encountered this issue when trying to unwrap a record. Test was using two chained pipelines (file -> kafka, kafka -> file).

2024-01-31T16:33:39+00:00 ERR node stopped error="node dest-log-ciy690a2b3921p0:foo stopped with error: error executing processor: failed to write message to DLQ: DLQ nack threshold exceeded (0/1), original error: unwrap: error unwrapping record: record payload after payload.after is not a map" component=pipeline.Service node_id=dest-log-ciy690a2b3921p0:foo stack=[{"file":"/Users/rb/code/conduitio/conduit/pkg/pipeline/lifecycle.go","func":"github.com/conduitio/conduit/pkg/pipeline.(*Service).runPipeline.func2","line":577},{"file":"/Users/rb/code/conduitio/conduit/pkg/pipeline/stream/processor.go","func":"github.com/conduitio/conduit/pkg/pipeline/stream.(*ProcessorNode).Run","line":68},{"file":"/Users/rb/code/conduitio/conduit/pkg/pipeline/stream/source_acker.go","func":"github.com/conduitio/conduit/pkg/pipeline/stream.(*SourceAckerNode).registerNackHandler.func1","line":129},{"file":"/Users/rb/code/conduitio/conduit/pkg/pipeline/stream/dlq.go","func":"github.com/conduitio/conduit/pkg/pipeline/stream.(*DLQHandlerNode).Nack","line":149},{"file":"/Users/rb/code/conduitio/conduit/pkg/processor/procbuiltin/unwrap.go","func":"github.com/conduitio/conduit/pkg/processor/procbuiltin.(*unwrapProcessor).Process","line":95},{"file":"/Users/rb/code/conduitio/conduit/pkg/processor/procbuiltin/unwrap.go","func":"github.com/conduitio/conduit/pkg/processor/procbuiltin.(*openCDCUnwrapper).UnwrapPayload","line":214}]

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[hariso]

🚀