CBLModel iOS Swift Issue

Greeting, I am trying to use the following code with the most recent version of Couchbase Lite on iOS. The class MuscleGroup extends CBLModel.

class func findByName(name : String) -> [MuscleGroup] {
  let query = MuscleGroupViews.muscleGroupByName.createQuery()
  var error: NSError?
  query.keys = [name]
  var found = query.run(&error)
  if (error != nil) {
  var result : [MuscleGroup] = []
  for row in found.allObjects as [CBLQueryRow] {
    print("-----> ")
    result += MuscleGroup(document: row.document)
  return result

When I try to run this the "result+= … " line fails with an error that says that the document already has a model. This happens if I have just created a new object of the MuscleGroup type but does not fail for any objects already in the database. So clearly I am doing something wrong. Can anyone give me any pointers on how one is supposed to use a view with CBLModel and return not the docuement objects but the model objects.

Thanks a bunch.