           }
 
         default:
-          assertionFailure("Unexpected case \(writer.sem.state.rawValue) in \(__FUNCTION__)")
+          continue
         }
       }
       OSSpinLockUnlock(&lock)

          }

        default:
          assertionFailure("Unexpected case \(writer.sem.state.rawValue) in \(__FUNCTION__)")
        }
      }
      while (tail &- nextget) > 0 || closed, let reader = readerQueue.dequeue()

        if writer.sem.setState(.Invalidated) { writer.sem.signal(); break }

      default:
        continue
      }
    }
    OSSpinLockUnlock(&lock)
