Supposed 'programmer' vibe-codes some program that generates XML.

Result: Malformed XML comes out of the program (this suggests that whatever the program does, it doesn't use an XML library correctly, or at all)

What to do?

Same 'programmer' solves the problem by vibe-coding a lenient XML-parser that accepts invalid XML.

Programming used to be about understanding a problem, thinking about edge-cases, and then writing a program that can solve the problem.