Fail early on empty input data in Report.run

[Si-ra-kri]

Summary

Adds early validation to fail with a clear error when empty DataFrames
are passed to Report.run.

Motivation

Passing empty input data currently results in a ZeroDivisionError deep
inside legacy drift calculations, which is confusing for users.

Changes

• Added input validation for empty DataFrames
• Added a unit test covering this case

Scope

• No API changes
• No metric logic changes

[github-actions]

📚 Artifacts deployed to GitHub Pages: https://evidentlyai.github.io/evidently/ci/#pr-1820-improve-input-validation

[Si-ra-kri]

All checks are green. Happy to make any adjustments if needed.

[DimaAmega]

Hi @Si-ra-kri

Thanks for contribution!
But you have an empty test tests/report/test_report_input_validation.py
Let's add a test case there and we will merge it

[Si-ra-kri]

Added a test case and pushed updates. Please let me know if anything else is needed 🙂

[DimaAmega]

@Si-ra-kri You have failed tests run https://evidentlyai.github.io/evidently/ci/pr-1820-improve-input-validation/pytest-html-report/