Google’s John Mueller said on Reddit that structured data is not a ranking factor. He also said on Twitter that errors in structured data code do not lead to penalties.
1. Structured data is not a ranking factor
“Just to set expectations, structured data generally wouldn’t be seen as a ranking factor — it’s just the search result that might be shown differently. Sometimes that difference is enough to make it worthwhile though :). Also, think about what it is that you want to achieve with it, don’t just do it because it’s possible.”
2. Errors in structured data code do not lead to penalties
On Twitter, Google’s John Mueller said that errors in structured data code do not lead to penalties as long as your structured data code is compliant with Google’s guidelines:
If the error in structured data results in the structured data not being compliant with our guidelines, then that's possible. Just having invalid markup wouldn't be a cause for a manual action there.— ? John ? (@JohnMu) August 27, 2019