java.lang.IllegalArgumentException: Null type

Hi Folks,

I'm trying to write a small scala (2.8.1) progam and run in inside of
the JEE Application Server (JBoss 6.0.0 Final). Even without the
program itself, as soon as I deploy the Scala libraries (WEB-INF\lib
\scala-dbc.jar, WEB-INF\lib\scala-library.jar, WEB-INF\lib\scala-
swing.jar) in a WAR file of the server I see the following Exception:

Caused by: java.lang.IllegalArgumentException: Null type
at
org.jboss.reflect.plugins.introspection.IntrospectionTypeInfoFactoryImpl.getTypeInfo(IntrospectionTypeInfoFactoryImpl.java:
354) [jboss-reflect.jar:2.2.0.GA]
at
org.jboss.reflect.plugins.introspection.IntrospectionTypeInfoFactoryImpl
$2.run(IntrospectionTypeInfoFactoryImpl.java:230) [jboss-reflect.jar:
2.2.0.GA]
at
org.jboss.reflect.plugins.introspection.IntrospectionTypeInfoFactoryImpl
$2.run(IntrospectionTypeInfoFactoryImpl.java:218) [jboss-reflect.jar:
2.2.0.GA]
at java.security.AccessController.doPrivileged(Native Method) [:
1.6.0_17]
at
org.jboss.reflect.plugins.introspection.IntrospectionTypeInfoFactoryImpl.getMethods(IntrospectionTypeInfoFactoryImpl.java:
217) [jboss-reflect.jar:2.2.0.GA]
at
org.jboss.reflect.plugins.ClassInfoImpl.getDeclaredMethods(ClassInfoImpl.java:
416) [jboss-reflect.jar:2.2.0.GA]
at
org.jboss.scanning.plugins.visitor.ClassHierarchyResourceVisitor.handleClass(ClassHierarchyResourceVisitor.java:
80) [:1.0.0.GA]
at
org.jboss.scanning.plugins.visitor.ReflectResourceVisitor.doVisit(ReflectResourceVisitor.java:
108) [:1.0.0.GA]
at
org.jboss.scanning.plugins.visitor.ReflectResourceVisitor.visit(ReflectResourceVisitor.java:
86) [:1.0.0.GA]
... 51 more

If I deploy the same artifact into JBoss 5.1.0 GA, it works without
any problems... Any ideas what I could do?

Many thanks,

Simon