plugin crash with abc.cpp:2240: ABCContext::buildTrait assert typeClass

[lirel]

Lightspark crashes when run from firefox.
When opening http://www.golem.de/1112/88150.html i get:

plugin-container: /build/buildd/lightspark-0.5.1/src/scripting/abc.cpp:2240: void lightspark::ABCContext::buildTrait(lightspark::ASObject*, const lightspark::traits_info*, bool, lightspark::IFunction*): Zusicherung »typeClass« nicht erfüllt.

this happens even when gnash(gui) is installed/uninstalled.
the gnash browser plugin is not present here.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: lightspark (not installed)
ProcVersionSignature: Ubuntu 3.0.0-13.22-generic 3.0.6
Uname: Linux 3.0.0-13-generic x86_64
ApportVersion: 1.23-0ubuntu4
Architecture: amd64
Date: Sat Dec 3 13:57:47 2011
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111011)
ProcEnviron:
 PATH=(custom, no user)
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SourcePackage: lightspark
UpgradeStatus: No upgrade log present (probably fresh install)