There is a warn-by-default Clippy lint for that: `clippy::for_loops_over_fallibles`. However, being an `IntoIterator` is important for things like flattening an

There is a warn-by-default Clippy lint for that: `clippy::for_loops_over_fallibles`. However, being an `IntoIterator` is important for things like flattening and other iterator adapters.