Interleave validates that elements/members of the otherSequences are non-null and throws ArgumentNullException claiming that otherSequences is null. It isn't common to validate contents for a sequence argument and so a null element inotherSequences should be left as an undefined behaviour.
Interleavevalidates that elements/members of theotherSequencesare non-null and throwsArgumentNullExceptionclaiming thatotherSequencesis null. It isn't common to validate contents for a sequence argument and so anullelement inotherSequencesshould be left as an undefined behaviour.