materialized dataset directory NPE

[Foxcapades]

java.lang.NullPointerException
   at vdi.core.s3.MaterializedDatasetDirectory$Companion.build-6L9Ad6M(MaterializedDatasetDirectory.kt:105)
   at vdi.core.s3.DatasetDirIterator.prepNext(DatasetDirIterator.kt:96)
   at vdi.core.s3.DatasetDirIterator.initFirstDataset(DatasetDirIterator.kt:43)
   at vdi.core.s3.DatasetDirIterator.<init>(DatasetDirIterator.kt:24)
   at vdi.core.s3.DatasetObjectStoreImpl.streamAllDatasets(DatasetObjectStoreImpl.kt:20)
   at vdi.core.reconciler.ReconcilerInstance.tryReconcile(ReconcilerInstance.kt:64)
   at vdi.core.reconciler.ReconcilerInstance.reconcile$dataset_reconciler(ReconcilerInstance.kt:42)
   at vdi.core.reconciler.Reconciler.runSlim(Reconciler.kt:96)
   at vdi.daemon.reconciler.ReconcilerImpl.runJob(ReconcilerImpl.kt:42)
   at vdi.core.modules.AbstractJobExecutor$run$2.invokeSuspend(AbstractJobExecutor.kt:34)

[Foxcapades]

The meta value is being asserted as non-null.

The assertion is incorrect as it may actually be null, however in this particular case it should not be null.

[Foxcapades]

It appears the directory builder is passing in object lists with only a single object 'delete-flag' before the error.

[Foxcapades]

cause was invalid dataset directories that contained only a delete flag. Error message needs to be improved.