Improve error handling in create-labels workflow

[Copilot]

Description

The create-labels.yaml workflow was silently ignoring all errors in the "dependencies" and "dotnet" label creation steps, which could mask authentication failures, rate limiting, or API issues.

Updated error handling to:

• Check specifically for already_exists errors (status 422)
• Log descriptive messages when labels already exist
• Re-throw all other errors with context for debugging

catch (error) {
  if (error.status === 422 && error.response?.data?.errors?.[0]?.code === 'already_exists') {
    console.log('Label "dependencies" already exists, skipping creation');
  } else {
    console.error('Failed to create label "dependencies":', error.message);
    throw error;
  }
}

This aligns error handling across all four label creation steps in the workflow.

Type of change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Refactor

How Has This Been Tested?

• YAML syntax validation with yamllint
• Automated code review
• CodeQL security scanning

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Screenshots (if applicable)

N/A

Additional context

Addresses review feedback from PR #27 about improving error visibility in GitHub Actions workflows.

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