Handle undefined hyperspherical mean directions

[FlorianPfaff]

Summary:

• Raise ValueError when a numerical first moment is effectively zero instead of normalizing it.
• Reuse the same normalization guard in the hyperhemispherical numerical mean-direction path.
• Add a regression test for the full-sphere uniform distribution, whose mean direction is undefined.

Testing: Not run locally because the changes were made through the GitHub connector without a local checkout.

[github-actions]

Test Results

0 tests  ±0   0 ✅ ±0   0s ⏱️ ±0s
0 suites ±0   0 💤 ±0 
0 files   ±0   0 ❌ ±0 

Results for commit 94c289a. ± Comparison against base commit 420306b.

♻️ This comment has been updated with latest results.

[github-actions]

✅MegaLinter analysis: Success

Descriptor	Linter	Files	Fixed	Errors	Warnings	Elapsed time
✅ COPYPASTE	jscpd	yes		no	no	19.4s
✅ JSON	prettier	2	0	0	0	0.44s
✅ JSON	v8r	2		0	0	2.46s
✅ MARKDOWN	markdownlint	28	0	0	0	1.38s
✅ MARKDOWN	markdown-table-formatter	28	0	0	0	0.37s
✅ PYTHON	bandit	571		0	0	9.76s
✅ PYTHON	black	571	31	0	0	18.31s
✅ PYTHON	flake8	571		0	0	6.39s
✅ PYTHON	isort	571	32	0	0	1.07s
✅ PYTHON	mypy	571		0	0	7.37s
✅ PYTHON	pylint	571		0	0	100.89s
✅ PYTHON	ruff	571	32	0	0	0.13s
✅ REPOSITORY	checkov	yes		no	no	26.17s
✅ REPOSITORY	gitleaks	yes		no	no	14.97s
✅ REPOSITORY	git_diff	yes		no	no	0.1s
✅ REPOSITORY	osv-scanner	yes		no	no	1.0s
✅ REPOSITORY	secretlint	yes		no	no	9.79s
✅ REPOSITORY	syft	yes		no	no	3.24s
✅ REPOSITORY	trivy-sbom	yes		no	no	4.08s
✅ REPOSITORY	trufflehog	yes		no	no	21.77s
✅ YAML	prettier	5	0	0	0	0.54s
✅ YAML	v8r	5		0	0	5.3s
✅ YAML	yamllint	5		0	0	0.49s

Notices

📣 MegaLinter 9.5.0 is out! Discover the new features and security recommendations in the release announcement. (Skip this info by defining SECURITY_SUGGESTIONS: false)

See detailed reports in MegaLinter artifacts

Your project could benefit from a custom flavor, which would allow you to run only the linters you need, and thus improve runtime performances. (Skip this info by defining FLAVOR_SUGGESTIONS: false)

• Documentation: Custom Flavors
• Command: npx mega-linter-runner@9.5.0 --custom-flavor-setup --custom-flavor-linters PYTHON_PYLINT,PYTHON_BLACK,PYTHON_FLAKE8,PYTHON_ISORT,PYTHON_BANDIT,PYTHON_MYPY,PYTHON_RUFF,COPYPASTE_JSCPD,JSON_V8R,JSON_PRETTIER,MARKDOWN_MARKDOWNLINT,MARKDOWN_MARKDOWN_TABLE_FORMATTER,REPOSITORY_CHECKOV,REPOSITORY_GIT_DIFF,REPOSITORY_GITLEAKS,REPOSITORY_OSV_SCANNER,REPOSITORY_SECRETLINT,REPOSITORY_SYFT,REPOSITORY_TRIVY_SBOM,REPOSITORY_TRUFFLEHOG,YAML_PRETTIER,YAML_YAMLLINT,YAML_V8R

Show us your support by starring ⭐ the repository

[FlorianPfaff]

@copilot Fix merge conflicts and CI/CD issues

[Copilot]

@copilot Fix merge conflicts and CI/CD issues

Done in 242bc00. I merged the latest main into this branch, resolved the remaining conflicts in the hypersphere subset files, and verified the previously failing CI areas locally on PYRECEST_BACKEND=pytorch (including test_hypercylindrical_dirac_distribution.py and test_kernel_sme_filter.py), which now pass.