Scala call length() on very long string throws exception: Maximum String literal length exceeded

I wrote a scala solution for HackerRank BigSorting ,
and got RuntimeException in some test case. I tested the input in scastie, it seems the problem is caused by calling length() on a very long string, but the same java solution has no problem, is this a bug?
my solution code is :

object Solution {
    def stringSort(x:String, y:String):Boolean = {
        var result = true

        if(x.length < y.length){
            result = true
        }else if(x.length > y.length){
            result = false
        }else{
            var founded = false
            var i = 0
            while(i < x.length && !founded){
                var xi = x.charAt(i)
                var yi = y.charAt(i)
                if(xi != yi){
                    result = xi < yi
                    founded = true
                }
                i += 1
            }
        }
        result
    }

    def bigSort(unsorted:Array[String]):Array[String] = {
        return unsorted.sortWith(stringSort)
    }

    def main(args: Array[String]) {
        val sc = new java.util.Scanner (System.in);
        var n = sc.nextInt();
        var unsorted = new Array[String](n);
        for(unsorted_i <- 0 to n-1) {
           unsorted(unsorted_i) = sc.next();
        }
        print(bigSort(unsorted).mkString("n"))
        // your code goes here
    }
}