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...