Unresolved Alias

[johnwargo]

I'm parsing some eleventy markdown documents to read the frontmatter using YAML and when my code gets to one of the documents, I get the following error: Unresolved alias (the anchor must be set before the alias). What does this mean? I've looked at my document content and I can't identify the issue.

[eemeli]

Your document contains an alias like *foo that's attempting to refer to a node with an anchor like &foo, which must be before the alias in the document.