Ensure tag-exists action works as intended

[frederikprijck]

Changes

The tag-exists action was not working due to the fact that it was trying to read from a step that did not exist. Without these changes, it would always 404 and act as if the tag doesn't exist.

Checklist

• [x] I have read the Auth0 general contribution guidelines
• [x] I have read the Auth0 Code of Conduct
• [x] All code quality tools/guidelines have been run/followed