message: Fix typing of ReplaceRelatedRecordOperation
diff: @@ -200,8 +200,9 @@ function mergeOperations(superceded: RecordOperation, superceding: RecordOperati
  }
  }
  }
  - } else if (equalRecordIdentities(superceded.relatedRecord, superceding.record)) {
  - if (superceding.op === 'removeRecord') {
  + } else if (superceding.record && superceding.op === 'removeRecord') {
  + if ((superceded as ReplaceRelatedRecordOperation).relatedRecord &&
  + equalRecordIdentities((superceded as ReplaceRelatedRecordOperation).relatedRecord, superceding.record)) {
  markOperationToDelete(superceded);
  }
  }
  