Bug fixes for the controls

Summary of Changes

I've made the following bug fixes in the controls:

1. If you set the min/max of the threshold to a zero-like value (e.g. 0.000) the UI won't overwrite what you've typed with "0".
2. If there are errors in the Pydantic config (e.g. the min is greater than the max), then the slice sliders will still work.

Checklist

• The MR has a clear and concise title
• Code is self-documented and follows style guidelines.
• Automated tests are written and pass successfully.
• Regression tests (e.g. manually triggered system tests, manual GUI/tool tests, ...) are performed to make sure the MR does not break anything (when applicable)
• Readme file is present and up-to-date.

Documentation Updates

Additional Notes

Closes #39 (closed) Closes #42 (closed)