   
   /**
    Create `stillImageoutput` and add it to `captureSession`.
-   - Throws: `CaptureManagerError.InvalidCaptureOutput` if the output cannot be added to `captureSession`.
+   - Throws: `CaptureManagerError.invalidCaptureOutput` if the output cannot be added to `captureSession`.
    */
   fileprivate func addStillImageOutput() throws {
     stillImageOutput = AVCaptureStillImageOutput()

  
  /**
   Create `videoInput` and add it to `captureSession`.
   - Throws: `CaptureManagerError.InvalidCaptureInput` if the input cannot be added to `captureSession`.
   */
  fileprivate func addVideoInput() throws {
    videoInput = try AVCaptureDeviceInput(device: videoDevice)

  
  /**
   Add `input` to `captureSession`.
   - Throws: `CaptureManagerError.invalidCaptureInput` if the input cannot be added to `captureSession`.
   */
  fileprivate func addCaptureInput(_ input: AVCaptureInput) throws {
    if (!captureSession.canAddInput(input)) {
