So any warnings about malformed input either
have to be opt-in, or there needs to be no errors. Either seems fine to me, just
don't foist
technical warnings or scary-looking red messages onto people who don't want them, or
know
how to resolve them.
That's why we make the warnings neither technical, nor red. And we
include in them instructions (and links to more instructions) on how
to resolve them.
Perhaps someone should talk to some real users about what they'd prefer...