Specify return value for undefined properties in workflow contexts

[rossjrw]

Why:

The documentation for workflows doesn't mention what happens when you access a nonexistent property. This is important to know - maybe it throws an error? It returns an empty string, so mentioning it will save someone an experiment to find out.

What's being changed:

Add a line to https://docs.github.com/en/actions/learn-github-actions/contexts.

Could possibly be more appropriate for https://docs.github.com/en/actions/learn-github-actions/expressions; however, I don't think there's a way to access a property in an expression without going via a context, so this seems fine.

Check off the following:

• I have reviewed my changes in staging (look for "Automatically generated comment" and click Modified to view your latest changes).
• For content changes, I have completed the self-review checklist.

Writer impact (This section is for GitHub staff members only):

• This pull request impacts the contribution experience
  • I have added the 'writer impact' label
  • I have added a description and/or a video demo of the changes below (e.g. a "before and after video")

[welcome]

Thanks for opening this pull request! A GitHub docs team member should be by to give feedback soon. In the meantime, please check out the contributing guidelines.

[github-actions]

Automatically generated comment ℹ️

This comment is automatically generated and will be overwritten every time changes are committed to this branch.

The table contains an overview of files in the content directory that have been changed in this pull request. It's provided to make it easy to review your changes on the staging site. Please note that changes to the data directory will not show up in this table.

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Content directory changes

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Source	Preview	Production	What Changed
content/actions/learn-github-actions/contexts.md	Modified	Original

[ramyaparimi]

@rossjrw
Thanks so much for opening a PR! I'll get this triaged for review ⚡

[github-actions]

Thanks for opening a pull request! We've triaged this issue for technical review by a subject matter expert 👀

[github-actions]

This is a gentle bump for the docs team that this PR is waiting for technical review.

[ethomson]

Thanks @rossjrw - I added a minor suggestion but this is a helpful improvement! 🎉

[felicitymay]

@rossjrw - thanks for this improvement to the page 💖

[github-actions]

Thanks very much for contributing! Your pull request has been merged 🎉 You should see your changes appear on the site in approximately 24 hours. If you're looking for your next contribution, check out our help wanted issues ⚡