 
                     // Inform delegate.
                     self.callbacksQueue.async {
-                        self.delegate.fetchingWillBegin(handle: handle)
+                        self.delegate?.fetchingWillBegin(handle: handle)
                     }
 
                     // Fetch the repo.

                        }

                        self.callbacksQueue.async {
                            self.delegate.handleWillUpdate(handle: handle)
                        }

                        try repo.fetch()

                        self.callbacksQueue.async {
                            self.delegate.handleDidUpdate(handle: handle)
                        }

                        return handle

    public let provider: RepositoryProvider

    /// The delegate interface.
    private let delegate: RepositoryManagerDelegate?

    /// The map of registered repositories.
    //
