Why does IntelliJ crash when using Scala plugin

I've just started using the Scala plugin, but find IntelliJ is crashing very frequently. One repeatable crash happens every time a test fails.
For example, running this crashes IntelliJ every time:

import org.scalatest.FunSuite

import org.junit.runner.RunWith

import org.scalatest.junit.JUnitRunner

@RunWith(classOf[JUnitRunner])

class IdeTestSuite extends FunSuite {

  test("a test") {

    assert(false)

  }

}

While this is fine:

import org.scalatest.FunSuite

import org.junit.runner.RunWith

import org.scalatest.junit.JUnitRunner

@RunWith(classOf[JUnitRunner])

class IdeTestSuite extends FunSuite {

  test("a test") {

    assert(true)

  }

}

I'm using IntelliJ 12.1.4, Java 1.7.0_21 and v        0.19.299 of the Scala plugin.

Log file is attached

Attachment(s):
idea.log.zip