### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [x] There is a reference to the original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake


The bug has already been reported and explained on the OpenCV forum:

- [optflow-calcopticalflowsparserlof-giving-assertion-error](https://forum.opencv.org/t/cv2-optflow-calcopticalflowsparserlof-giving-assertion-error/4835)
- [calcopticalflowsparserlof-assertion-error-in-initialflow](https://forum.opencv.org/t/calcopticalflowsparserlof-assertion-error-in-initialflow/8669)

The bug is manifested only if 'UseInitialFlow' is set to true and 'ForwardBackwardThreshold' > 0 (enabled).

…_from_aruco

remove charuco duplication

Omnidir calibration: uncertainty fixed