SIGTSTP! Life,the universe , and Everything

Here is my code:

object Main extends App {
    import scala.util.control.Breaks._
    import scala.io.StdIn
    import java.io.EOFException
    breakable {
        while(true){
            try{
                val num = StdIn.readInt()
                if(num==42){    
                    break
                }
                println(num)
            }catch{
                case x:EOFException => {"null value"}
            }
        }
    }
}

Working fine in sample. Why I get below error on CodeChef?

RUNTIME ERROR : SIGTSTP

Say, if there was no 42, your program would keep on trying to read input and failing, right?