message: fix ModelStructureRepresentation.getParams for structures without assebmlies
diff: @@ -24,7 +24,7 @@ export namespace ModelStructureRepresentation {
  deposited: PD.EmptyGroup(),
  assembly: PD.Group({
  id: PD.Optional(model
  - ? PD.Select(assemblyIds[0][0], assemblyIds, { label: 'Asm Id', description: 'Assembly Id' })
  + ? PD.Select(assemblyIds.length ? assemblyIds[0][0] : '', assemblyIds, { label: 'Asm Id', description: 'Assembly Id' })
  : PD.Text('', { label: 'Asm Id', description: 'Assembly Id (use empty for the 1st assembly)' }))
  }, { isFlat: true }),
  'symmetry-mates': PD.Group({
  