Null is a subtype of all reference types. It is a subtype of all AnyRef types to provide a type for the keyword null.
Scala does not have a null keyword.
For instance, it is not possible to assign null to a variable of type scala.Int.
Nothing provides a compatible return type for operations that affect a program's flow.
One of the usages of Nothing is that it signals abnormal termination.
Any time you feel like using a