Yes, indeed:

#5  0xb050e020 in Filter (this=0x87c0180, filter=0x0)
    at /home/boud/koffice/1.6/koffice/krita/plugins/viewplugins/scripting/kritacore/krs_filter.cpp:31
#6  0xb04e8a94 in Kross::KritaCore::KritaCoreFactory::getFilter (
    this=0x8b2f7e0, args=@0xbfdfbf0c)
    at /home/boud/koffice/1.6/koffice/krita/plugins/viewplugins/scripting/kritacore/kritacoremodule.cpp:157
#7  0xb04ef38d in Kross::Api::Function0<Kross::KritaCore::KritaCoreFactory>::call (this=0x87c3dc8, args=@0xbfdfbf40) at function.h:68
#8  0xb04ef003 in Kross::Api::Event<Kross::KritaCore::KritaCoreFactory>::call
    (this=0x8b2f7e0, name=@0xbfdfc018, arguments=@0xbfdfbf94) at event.h:212
#9  0xb04e8be1 in Kross::KritaCore::KritaCoreModule::call (this=0x8a51ac0, 
    name=@0xbfdfc018, arguments=@0xbfdfc070)
    at /home/boud/koffice/1.6/koffice/krita/plugins/viewplugins/scripting/kritacore/kritacoremodule.cpp:279
#10 0xb06d8e4b in Kross::Python::PythonExtension::proxyhandler (
    _self_and_name_tuple=0xb053c18c, args=0xb053c86c)
    at /home/boud/koffice/1.6/koffice/lib/kross/python/pythonextension.cpp:427
#11 0xb05f7c13 in PyCFunction_Call () from /usr/lib/libpython2.4.so.1.0
#12 0xb063202e in PyEval_EvalFrame () from /usr/lib/libpython2.4.so.1.0
#13 0xb0633c46 in PyEval_EvalCodeEx () from /usr/lib/libpython2.4.so.1.0
#14 0xb05e54f9 in PyFunction_SetClosure () from /usr/lib/libpython2.4.so.1.0
#15 0xb05cae3e in PyObject_Call () from /usr/lib/libpython2.4.so.1.0
#16 0xb05d2a7b in PyMethod_New () from /usr/lib/libpython2.4.so.1.0
#17 0xb05cae3e in PyObject_Call () from /usr/lib/libpython2.4.so.1.0
#18 0xb062cbc8 in PyEval_CallObjectWithKeywords ()
   from /usr/lib/libpython2.4.so.1.0
#19 0xb05d4d52 in PyInstance_New () from /usr/lib/libpython2.4.so.1.0
#20 0xb05cae3e in PyObject_Call () from /usr/lib/libpython2.4.so.1.0
#21 0xb063064c in PyEval_EvalFrame () from /usr/lib/libpython2.4.so.1.0
#22 0xb0633c46 in PyEval_EvalCodeEx () from /usr/lib/libpython2.4.so.1.0
#23 0xb0633e96 in PyEval_EvalCode () from /usr/lib/libpython2.4.so.1.0
#24 0xb06e935f in Kross::Python::PythonScript::execute (this=0x8b88538)
    at /home/boud/koffice/1.6/koffice/lib/kross/python/pythonscript.cpp:309
#25 0xb0ce97c0 in Kross::Api::ScriptContainer::execute (this=0x87c9208)
    at /home/boud/koffice/1.6/koffice/lib/kross/main/scriptcontainer.cpp:181
#26 0xb0cf3da0 in Kross::Api::ScriptAction::activate (this=0x87c91d8)
    at /home/boud/koffice/1.6/koffice/lib/kross/main/scriptaction.cpp:228
#27 0xb0cf6018 in Kross::Api::ScriptGUIClient::executeScriptAction (
    this=0x89d6a40, action=@0xbfdfcc4c)
    at /home/boud/koffice/1.6/koffice/lib/kross/main/scriptguiclient.cpp:369
#28 0xb0cf614d in Kross::Api::ScriptGUIClient::executeScriptFile (
    this=0x89d6a40, file=@0xbfdfccac)
    at /home/boud/koffice/1.6/koffice/lib/kross/main/scriptguiclient.cpp:359
#29 0xb0cf9e83 in Kross::Api::ScriptGUIClient::executeScriptFile (
    this=0x89d6a40)
    at /home/boud/koffice/1.6/koffice/lib/kross/main/scriptguiclient.cpp:350
#30 0xb0cfa2d0 in Kross::Api::ScriptGUIClient::qt_invoke (this=0x89d6a40, 
    _id=5, _o=0xbfdfcddc) at scriptguiclient.moc:183
#31 0xb71bceb9 in QObject::installEventFilter ()

SVN commit 600105 by berger:

forward port: don't crash when trying to access a non existent filter
CCBUG:136461


 M  +6 -1      kritacoremodule.cpp  


--- trunk/koffice/krita/plugins/viewplugins/scripting/kritacore/kritacoremodule.cpp #600104:600105
@@ -192,7 +192,12 @@
 QObject* KritaCoreModule::filter(const QString& filtername)
 {
     KisFilter* filter = KisFilterRegistry::instance()->get(filtername).data();
-    return new Filter(this, filter);
+    if(filter)
+    {
+        return new Filter(this, filter);
+    } else {
+      return 0;
+    }
 }
 
 QObject* KritaCoreModule::createImage(int width, int height, const QString& colorspace, const QString& name)

SVN commit 600106 by berger:

don't crash when trying to access a non existent filter
BUG:136461


 M  +6 -1      kritacoremodule.cpp  


--- branches/koffice/1.6/koffice/krita/plugins/viewplugins/scripting/kritacore/kritacoremodule.cpp #600105:600106
@@ -154,7 +154,12 @@
 {
     QString name = Kross::Api::Variant::toString(args->item(0));
     KisFilter* filter = KisFilterRegistry::instance()->get(name);
-    return new Filter(filter);
+    if(filter)
+    {
+      return new Filter(filter);
+    } else {
+      return 0;
+    }
 }
 
 Kross::Api::Object::Ptr KritaCoreFactory::newCircleBrush(Kross::Api::List::Ptr args)