why exceptions extends scala.util.control.ControlThrowable?

[comefortest]

The exceptions which extends scala.util.control.ControlThrowable, break out some scala control constructs, such as scalax.file.NotDirectoryException. When I use scala-io for something in a future, if a scalax.file.NotDirectoryException is thrown, then the "onComplete" of the generated future will not be triggered. scala.util.control.ControlThrowable, which is for BASIC control flows such as "IF-ELSE", "RETURN", "BREAK", "FUTRUEN", is not for scala-io.