try {
          ThroughWLModel = getModel(attrDef.through, orm);
        } catch (e){ throw new Error('Consistency violation: The referenced attribute (`'+attrName+'`, from model `'+modelIdentity+'`) is a "through" association, because it declares a `through`.  But the junction model it references as "through" (`'+attrDef.through+'`) is missing or invalid.  Details: '+e.stack); }