Debugging in Webstorm with Chrome extension causes an IllegalArgumentException

I have the Chrome extension from jetbrains installed.

- When I right click my karma.conf.js and Run the tests everything is fine :)

- When I debug the tests wait some seconds til the browser pops us and click a breakpoint at a line of my unit tests I see this message added to the event log window: :(

21:17:21 IllegalArgumentException: Argument 0 for @NotNull parameter of com/intellij/chromeConnector/debugger/LineBreakpointManagerImpl.createTarget must not be null: Argument 0 for @NotNull parameter of com/intellij/chromeConnector/debugger/LineBreakpointManagerImpl.createTarget must not be null

What do I wrong? I am using WebStorm 8 Beta.