Make waitForCompletionOfOperationWithID re-throw error

This is what its documentation says it does, but I mistakenly didn’t do
it in e3dcfe1. (It didn’t actually matter because nobody currently uses
the error that this method throws; they will do in an upcoming commit,
though.)

Sources/AblyChat/RoomLifecycleManager.swift

@@ -604,6 +604,7 @@ internal actor DefaultRoomLifecycleManager<Contributor: RoomLifecycleContributor
             logger.log(message: "Operation \(waitingOperationID) completed waiting for result of operation \(waitedOperationID), which completed successfully", level: .debug)
         } catch {
             logger.log(message: "Operation \(waitingOperationID) completed waiting for result of operation \(waitedOperationID), which threw error \(error)", level: .debug)
+            throw error
         }
     }