Function new_boxed_slice_from_fallible_iter 

pub fn new_boxed_slice_from_fallible_iter<T, E>(
    iter: impl IntoIterator<Item = Result<T, E>>,
) -> Result<Box<[T]>, BoxedSliceFromFallibleIterError<E>>

Create a Box<[T]> from the given iterator’s Result<T, E> items.

Returns an error on allocation failure or if an iterator item is an Err.