fix: only setFailed when actor not null (#1399) #2570

Job	Run time
Compile (testkit/Test/compile actor-tests/Test/compile)	5m 12s
Compile (actor-testkit-typed/Test/compile actor-typed-tests/Test/compile)	4m 58s
Compile (bench-jmh/Test/compile)	7m 9s
Compile (cluster/Test/compile cluster-tools/Test/compile cluster-typed/Test/compile distributed-d...	8m 5s
Compile (discovery/Test/compile coordination/Test/compile)	5m 24s
Compile (persistence/Test/compile persistence-shared/Test/compile persistence-query/Test/compile ...	9m 39s
Compile (pki/Test/compile slf4j/Test/compile)	4m 46s
Compile (serialization-jackson/Test/compile)	5m 49s
Compile (stream/Test/compile stream-testkit/Test/compile stream-tests/Test/compile stream-typed/T...	7m 33s
Compile (stream-tests-tck/Test/compile)	5m 23s
Compile (remote/Test/compile remote-tests/Test/compile protobuf/Test/compile protobuf-v3/Test/com...	6m 45s
	1h 10m 43s

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