FIX: error on query for `common_rupture_set`

[chrisbc]

in TEST

query avg{
  node (id:"QWdncmVnYXRlSW52ZXJzaW9uU29sdXRpb246MTAxMTMw") {
    ... on AggregateInversionSolution{
      predecessors {
        id, relationship
      }
      meta {
        k
        v
      }
      common_rupture_set
    }
  }
}