# Description

While working on a task I made a tiny typo in the scale randomization
range for the stiffness-gain parameter. The robot still spawned, but its
behaviour was utterly bizarre. It only took a minute to spot the
mistake, yet it made me realize we have no guard-rails for this sort of
edge case.

This PR introduces a lightweight check that verifies, when
operation=="scale", the lower bound is non-negative and the upper bound
is not smaller than the lower one. Right now I cover the most common
parameters (stiffness, damping, mass, tendon gains, etc.), basically
anything that must stay positive to make physical sense.

If you’d like the same safeguard applied to other parameter types just
let me know and I’ll happily extend the patch.

## Type of change

- Bug fix (non-breaking change which fixes an issue)
- New feature (non-breaking change which adds functionality)

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [x] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [x] I have added tests that prove my fix is effective or that my
feature works
- [ ] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

---------
Signed-off-by: Louis LE LAY <le.lay.louis@gmail.com>
Signed-off-by: ooctipus <zhengyuz@nvidia.com>
Co-authored-by: louislelay <louislelay@pal-robotics.com>
Co-authored-by: ooctipus <zhengyuz@nvidia.com>