Official stance on how to return errors

[dev-ardi]

What it does

return Err(ErrKind::Foo.into()) and Err(ErrKind::Foo)? are both accepted.
There shouldn't be two ways of doing the same thing and the latter is more succint.

Advantage

• Less code
• Unified way of doing things

Drawbacks

• Can be annoying.
• Unclear if we want to emit where there's no .into()

Example

return Err(ErrKind::Foo.into())

Could be written as:

Err(ErrKind::Foo)?