There are 3 different cases of var v: T = null:
  1. v is an optional value
    - use Option[T] type, which is idiomatic and type safe,
  2. v is an uninitialized value (a value must be assigned)
    - use _ as initializer, which is clear, concise, and platform-independent,
  3. it's a performance optimization (you actually use null value)
    - explicitly suppressed the inspection for the unsafe code.