[BUG] Fix single trace zero division error

[sstephanyy]

Description

To prevent the ZeroDivisionError from occurring when using index-based colormodes with a single trace or a single row of data, the code has been modified to check the number of rows before performing any calculations. If only one row is present, a default color value (like 0.0) is returned instead of attempting to divide by zero.

Related issues

Closes #252

PR check list

• Read the contributing guidelines.
  • You don't have to read the whole thing, but it's a good idea to skim it. And definitely take a look at it if you're experiencing any issues getting your local environment up and running.
• Provided the relevant details in the PR's description.
• Referenced relevant issues in the PR's description.
• Added tests for all my changes.
  • The CI will fail unless 100% of all new code is covered by the tests.
• Updated the docs for relevant changes.
  • New modules (or renamed ones) are included in docs/api/internal/.
  • New public functions/classes/variables are documented in docs/api/index.rst.
  • Added the appropriate versionadded, versionchanged, or deprecated directives to docstrings.
    • The version should be the next release version, which you can infer by bumping the minor version in MAJOR.MINOR.PATCH (e.g., if the current version is 0.2.3, the next release will be 0.3.0).
• Changes are documented in docs/reference/changelog.md.
  • Please try to follow the conventions laid out in the file. In doubt, just ask!
• Consider granting push permissions to your PR's branch, so maintainers can help you out if needed.
• The CI check are all passing, or I'm working on fixing them!
• I have reviewed my own code! 🤠

---

📚 Documentation preview 📚: https://ridgeplot--268.org.readthedocs.build/en/268/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (8196584) to head (7c6ebdb).
Report is 139 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #268   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           13        13           
  Lines          537       541    +4     
  Branches        70        72    +2     
=========================================
+ Hits           537       541    +4     

Flag	Coverage Δ
combined-src	99.26% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[tpvasconcelos]

@sstephanyy just noticed that you added your changes to the wrong section of the changelog. No worries of course but this would mean that your changes would not be listed in the next release notes 😨

Fixed in bba6be2 ✅

[tpvasconcelos]

@sstephanyy I simplified your test cases a bit by using pytest.mark.parametrize (take a look).

[sstephanyy]

@sstephanyy just noticed that you added your changes to the wrong section of the changelog. No worries of course but this would mean that your changes would not be listed in the next release notes 😨

Fixed in bba6be2 ✅

Thanks so much for the fix :)

[sstephanyy]

@sstephanyy I simplified your test cases a bit by using pytest.mark.parametrize (take a look).

wow, well-done. I do know about the existence of pytest.mark.parametrize to run the same test over and over again with different values, but didn't come to my mind using it. Great job 😮 🎊

[tpvasconcelos]

@sstephanyy let me know if the new test cases I pushed were helpful or whether you want more help here 👍

See this as well

[tpvasconcelos]

Thank you @sstephanyy for your work here!