NullPointerException when deploying on Tomcat 6

[Sybren]

Dear group,

This is my first post here, so I'll introduce myself. My name is
Sybren, and I work for an IT company in The Netherlands. We're going
to use the Play Framework for the first time, and I'm very
enthousiastic about it!

On the production servers, Play will be run as a webapp inside Tomcat
6. I've tried to deploy it using::

play war -o /opt/apache-tomcat-6/webapps/yabe

When starting Tomcat, I get a NullPointerException in the logging.
Here is the last bit of the stack trace:

Caused by: java.lang.NullPointerException
at play.classloading.enhancers.Enhancer.isScala(Enhancer.java:
188)
at
play.classloading.enhancers.SigEnhancer.enhanceThisClass(SigEnhancer.java:
20)
at play.CorePlugin.enhance(CorePlugin.java:296)
... 30 more

The full log output, including the full stack trace, is at
http://pastebin.com/t33yd6dd

This is on my development machine. I have one JDK (Sun's JDK version
1.6.0-26) which is used by the compiler as well as Tomcat. The
application works fine with "play run".

Can anyone help me fix this?

With kind regards,
Sybren