relativize shouldn't return null

[johnomalley]

The following returns null:

val a = Path.fromString("/Users")
val b = Path.fromString("/etc")
a.relativize(b)

I think there's an implicit guarantee not to return null from a scala API. I think relativize should be either deprecated or fixed. Some suggestions:

• deprecate relativize and add relativizeOption (if backward compatibility is a must)
• change relativize to throw an exception if it's not possible to relativize (maybe add relativizeOption as well).
• change relativize to return an Option[Path]

[dcsobral]

I entirely agree. I'd never expect any of this API to return null.

[jesseeichar]

I absolutely agree with that. I will make the change.