When a Blueprint fails to execute, it seems like a bug in Playground. Sometimes it is, but sometimes it's a developer error, e.g. downloading a non-existent file. Let's clearly communicate any Blueprint execution problems to the user directly in the UI so they at least know what went wrong.

Ideally, these two could be tackled too:

• Devex: Console.log an explanation of CORS issues to clarify why, e.g., zips from GitHub urls cant be downloaded #1205
• Improve error messaging when Playground Block is used on non-ssl site #973

Related:

• Playground Tools: Console Logger - display console errors in the post editor #1164