fix from stable - was missing a NULL check

source/blender/python/api2_2x/NLA.c

@@ -221,6 +221,7 @@ static PyObject *Action_getFrameNumbers(BPy_Action *self)
 	
 	py_list = PyList_New(0);
 	for(achan = self->action->chanbase.first; achan; achan = achan->next){
+		if (achan->ipo) {
 			for (icu = achan->ipo->curve.first; icu; icu = icu->next){
 				bezt= icu->bezt;
 				if(bezt) {
@@ -237,6 +238,7 @@ static PyObject *Action_getFrameNumbers(BPy_Action *self)
 				}
 			}
 		}
+	}
 	PyList_Sort(py_list);
 	return EXPP_incr_ret(py_list);
 }