if (!OtherWLModel.attributes[attrDef.via]) {
          throw new Error('Consistency violation: The referenced attribute (`'+attrName+'`, from model `'+modelIdentity+'`) is an association, because it declares a `collection`.  But that association also specifies a `via` ('+attrDef.via+'`) which does not correspond with a recognized attribute on the other model (`'+attrDef.collection+'`)');
        }