def max(x: Int, y: Int): Int =  {
  if(x > y) x
  else y
}

Internal error: java.lang.NoClassDefFoundError: scala/Serializable
org.jetbrains.jps.incremental.scala.remote.ClientEventProcessor.process(ClientEventProcessor.scala:22)
org.jetbrains.jps.incremental.scala.remote.RemoteResourceOwner.handle(RemoteResourceOwner.scala:47)
org.jetbrains.jps.incremental.scala.remote.RemoteResourceOwner.handle$(RemoteResourceOwner.scala:37)
org.jetbrains.plugins.scala.compiler.RemoteServerRunner.handle(RemoteServerRunner.scala:16)
org.jetbrains.jps.incremental.scala.remote.RemoteResourceOwner.$anonfun$send$5(RemoteResourceOwner.scala:30)
org.jetbrains.jps.incremental.scala.remote.RemoteResourceOwner.$anonfun$send$5$adapted(RemoteResourceOwner.scala:29)
org.jetbrains.jps.incremental.scala.package$.using(package.scala:21)
org.jetbrains.jps.incremental.scala.remote.RemoteResourceOwner.$anonfun$send$3(RemoteResourceOwner.scala:29)
org.jetbrains.jps.incremental.scala.remote.RemoteResourceOwner.$anonfun$send$3$adapted(RemoteResourceOwner.scala:25)
org.jetbrains.jps.incremental.scala.package$.using(package.scala:21)
org.jetbrains.jps.incremental.scala.remote.RemoteResourceOwner.$anonfun$send$2(RemoteResourceOwner.scala:25)
org.jetbrains.jps.incremental.scala.remote.RemoteResourceOwner.$anonfun$send$2$adapted(RemoteResourceOwner.scala:24)
org.jetbrains.jps.incremental.scala.package$.using(package.scala:21)
org.jetbrains.jps.incremental.scala.remote.RemoteResourceOwner.send(RemoteResourceOwner.scala:24)
org.jetbrains.jps.incremental.scala.remote.RemoteResourceOwner.send$(RemoteResourceOwner.scala:22)
org.jetbrains.plugins.scala.compiler.RemoteServerRunner.send(RemoteServerRunner.scala:16)
org.jetbrains.plugins.scala.compiler.RemoteServerRunner$$anon$1.$anonfun$run$1(RemoteServerRunner.scala:36)
scala.collection.immutable.Range.foreach$mVc$sp(Range.scala:155)
org.jetbrains.plugins.scala.compiler.RemoteServerRunner$$anon$1.run(RemoteServerRunner.scala:32)
org.jetbrains.plugins.scala.worksheet.server.RemoteServerConnector.compileAndRun(RemoteServerConnector.scala:111)
org.jetbrains.plugins.scala.worksheet.processor.WorksheetCompiler$$anon$3.run(WorksheetCompiler.scala:61)
com.intellij.compiler.progress.CompilerTask.run(CompilerTask.java:185)
com.intellij.openapi.progress.impl.CoreProgressManager$TaskRunnable.run(CoreProgressManager.java:731)
com.intellij.openapi.progress.impl.CoreProgressManager.lambda$runProcess$2(CoreProgressManager.java:164)
com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:586)
com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:532)
com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:86)
com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:151)
com.intellij.openapi.progress.impl.CoreProgressManager$4.run(CoreProgressManager.java:403)
com.intellij.openapi.application.impl.ApplicationImpl$1.run(ApplicationImpl.java:311)
java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
java.util.concurrent.FutureTask.run(FutureTask.java:266)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
java.lang.Thread.run(Thread.java:748)