This release adds a new step to parsing the issue template, to validate the frontmatter in your template against a defined schema. That way, any missing or invalid fields (like a missing title) will be caught and get a proper error message.
I'm not marking this as a breaking change because the expected schema hasn't changed, now it's just enforcing it. Apologies if this does break anyones templates, but that's a good thing as it'd be pointing out something invalid about it!