Intermittently failing test in OrganismPartSearchDaoIT

[ke4]

There is a NPE in the failed test case:

java.lang.NullPointerException
	at uk.ac.ebi.atlas.solr.SingleCellSolrUtils.lambda$getRandomCellTypesFromQueryResult$0(SingleCellSolrUtils.java:62)
	at java.base/java.util.stream.IntPipeline$1$1.accept(IntPipeline.java:180)
	at java.base/java.util.Spliterators$IntArraySpliterator.forEachRemaining(Spliterators.java:1032)
	at java.base/java.util.Spliterator$OfInt.forEachRemaining(Spliterator.java:699)
	at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
	at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
	at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913)
	at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578)
	at uk.ac.ebi.atlas.solr.SingleCellSolrUtils.getRandomCellTypesFromQueryResult(SingleCellSolrUtils.java:63)
	at uk.ac.ebi.atlas.solr.SingleCellSolrUtils.fetchedRandomCellTypesByCellIDs(SingleCellSolrUtils.java:37)
	at uk.ac.ebi.atlas.search.organismpart.OrganismPartSearchDaoIT.whenValidCellIdsAndValidCellTypesProvidedReturnSetOfOrganismPart(OrganismPartSearchDaoIT.java:120)