npm packages cannot be migrated due to IllegalStateException PackageVersion expected when contained in a rebuilt hosted repository

2016-11-15 10:24:30,150+1100 WARN [plan-executor-4-thread-3] admin com.sonatype.nexus.migration.repository.ProcessChangesStep - Process changes failed
javax.ws.rs.InternalServerErrorException: HTTP 500 Internal Server Error

2016-11-15 10:24:30 WARN [qtp625399792-185] *UNKNOWN org.sonatype.sisu.siesta.server.internal.mappers.ThrowableExceptionMapper - java.lang.IllegalStateException: PackageVersion expected for npm tarball /auspost-array-includes/-/auspost-array-includes-1.0.0.tgz
java.lang.IllegalStateException: PackageVersion expected for npm tarball /auspost-array-includes/-/auspost-array-includes-1.0.0.tgz
at com.google.common.base.Preconditions.checkState(Preconditions.java:200) ~[guava-16.0.1.jar:na]
at com.sonatype.nexus.migrationagent.repository.migrators.NpmRepositoryMigrator.findVersion(NpmRepositoryMigrator.java:85) ~[na:na]
at com.sonatype.nexus.migrationagent.repository.migrators.NpmRepositoryMigrator.extract(NpmRepositoryMigrator.java:63) ~[na:na]
at com.sonatype.nexus.migrationagent.repository.RepositoryMigratorSupport.extract(RepositoryMigratorSupport.java:248) ~[na:na]
at com.sonatype.nexus.migrationagent.repository.RepositoryMigrator$extract.call(Unknown Source) ~[na:na]