Error: [$compile:nonassign] http://errors.angularjs.org/1.5.8/$compile/nonassign?p0=open%20%3D%3D%20menu.id_menu%20%3F%20true%20%3A%20false&p1=isOpen&p2=uibAccordionGroup

<div ng-repeat="menu in respostaListaMenus">
            <div ng-if="menu.subitens_menu == 1">
                <uib-accordion>
                    <uib-accordion-group is-open="open == menu.id_menu ? true : false">
                        <uib-accordion-heading>
                            <div ng-click="abreMenu(menu.id_menu)">
                                <i class="fa {{menu.icone_menu_rel}}"></i>{{menu.nome_menu_rel}}<i class="pull-right glyphicon" ng-class="{'glyphicon-chevron-down': status.open1, 'glyphicon-chevron-right': !status.open1}"></i>
                            </div>
                        </uib-accordion-heading>
                        <div ng-repeat="submenu in respostaListaMenus" ng-if="submenu.id_pai_menu == menu.id_menu" ng-click="buscaDestino(submenu.id_menu_rel)">
                            <a href="#{{submenu.link_menu_rel}}">
                                <div class="item" id="{{submenu.nome_permissao_menu_rel}}">{{submenu.nome_menu_rel}}</div>
                            </a>
                        </div>
                    </uib-accordion-group>
                </uib-accordion>
            </div>
            <div ng-if="menu.id_pai_menu == 0 && menu.link_menu_rel != ''" ng-click="buscaDestino(menu.id_menu_rel)">
                <a href="#{{menu.link_menu_rel}}">
                    <div class="item" id="{{menu.nome_permissao_menu_rel}}"><i class="fa {{menu.icone_menu_rel}}"></i>{{menu.nome_menu_rel}}</div>
                </a>
            </div>
        </div>

$scope.abreMenu = function(idMenu){
        $scope.open = idMenu;
    }

$scope.listaMenusSelecao = function(){
            AppService.listaMenus().then(function(response) {
                $scope.respostaListaMenusSelecao = response.data;
                for (var i = 0; i < $scope.respostaListaMenusSelecao.length; i++) {
                    if($scope.respostaListaMenusSelecao[i].link_menu_rel != ''){
                        if($scope.idMenu == $scope.respostaListaMenusSelecao[i].id_menu){
                            console.log($scope.respostaListaMenusSelecao[i]);
                            $scope.open = $scope.respostaListaMenusSelecao[i].id_pai_menu;
                        }
                    }
                }
            }, function(error) {
                console.error(error);
            });
        }