"stressVersion" command of gatling-dse-stress fails

[yabinmeng]

$ java -jar gatling-dse-stress-assembly-1.2.6.jar stressVersion
Exception in thread "main" java.lang.NullPointerException
at java.io.Reader.(Reader.java:78)
at java.io.InputStreamReader.(InputStreamReader.java:129)
at scala.io.BufferedSource.reader(BufferedSource.scala:22)
at scala.io.BufferedSource.bufferedReader(BufferedSource.scala:23)
at scala.io.BufferedSource.charReader$lzycompute(BufferedSource.scala:33)
at scala.io.BufferedSource.charReader(BufferedSource.scala:31)
at scala.io.BufferedSource.scala$io$BufferedSource$$decachedReader(BufferedSource.scala:60)
at scala.io.BufferedSource$BufferedLineIterator.(BufferedSource.scala:65)
at scala.io.BufferedSource.getLines(BufferedSource.scala:84)
at com.datastax.gatling.stress.Starter$.stressVersion(Starter.scala:77)
at com.datastax.gatling.stress.Starter$.main(Starter.scala:64)
at com.datastax.gatling.stress.Starter.main(Starter.scala)

From the problematic code, it seems that it is looking for and prints the contents of a file: "/version.txt".