在21.7.7版本中安装ZAI插件，插件页面功能异常怎么解决？解决中悬赏5积分

如题，在在21.7.7版本中安装ZAI插件，提示安装成功，页面刷新后无法进入后台管理页面了，报一下异常信息，怎么解决？

Fatal error: Uncaught Error: Attempt to assign property "zai" on null in /apps/zentao/extension/custom/admin/ext/lang/zh-cn/ai.php:3 Stack trace: #0 /apps/zentao/framework/base/router.class.php(2956): include() #1 /apps/zentao/framework/router.class.php(139): baseRouter->loadLang('admin', '') #2 /apps/zentao/framework/base/model.class.php(159): router->loadLang('admin', '') #3 /apps/zentao/framework/base/router.class.php(2536): baseModel->__construct('') #4 /apps/zentao/framework/base/control.class.php(320): baseRouter->loadTarget('admin', '') #5 /apps/zentao/framework/control.class.php(171): baseControl->loadModel('admin') #6 /apps/zentao/lib/zin/wg/dropmenu/v1.php(163): control->loadModel('admin') #7 /apps/zentao/lib/zin/core/node.class.php(483): zin\dropmenu->build() #8 /apps/zentao/lib/zin/core/node.class.php(463): zin\node->buildContents() #9 /apps/zentao/lib/zin/core/node.class.php(894): zin\node->prebuild() #10 /apps/zentao/lib/zin/core/node.class.php(462): zin\prebuild(Array, Object(zin\h)) #11 /apps/zentao/lib/zin/core/node.class.php(894): zin\node->prebuild() #12 /apps/zentao/lib/zin/core/node.class.php(463): zin\prebuild(Array, Object(zin\heading)) #13 /apps/zentao/lib/zin/core/node.class.php(894): zin\node->prebuild() #14 /apps/zentao/lib/zin/core/node.class.php(462): zin\prebuild(Array, Object(zin\h)) #15 /apps/zentao/lib/zin/core/node.class.php(894): zin\node->prebuild() #16 /apps/zentao/lib/zin/core/node.class.php(462): zin\prebuild(Array, Object(zin\h)) #17 /apps/zentao/lib/zin/core/node.class.php(894): zin\node->prebuild() #18 /apps/zentao/lib/zin/core/node.class.php(463): zin\prebuild(Array, Object(zin\header)) #19 /apps/zentao/lib/zin/core/node.class.php(894): zin\node->prebuild() #20 /apps/zentao/lib/zin/core/node.class.php(462): zin\prebuild(Array, Object(zin\h)) #21 /apps/zentao/lib/zin/core/node.class.php(894): zin\node->prebuild() #22 /apps/zentao/lib/zin/core/node.class.php(462): zin\prebuild(Array, Object(zin\h)) #23 /apps/zentao/lib/zin/core/node.class.php(894): zin\node->prebuild() #24 /apps/zentao/lib/zin/core/node.class.php(463): zin\prebuild(Array, Object(zin\page)) #25 /apps/zentao/lib/zin/core/context.class.php(392): zin\node->prebuild(true) #26 /apps/zentao/lib/zin/core/render.func.php(68): zin\context->render(Object(zin\page), NULL, 'html') #27 /apps/zentao/framework/base/control.class.php(1053): zin\renderPage() #28 /apps/zentao/framework/base/control.class.php(962): baseControl->render('convert', 'index') #29 /apps/zentao/module/convert/control.php(50): baseControl->display() #30 /apps/zentao/framework/base/router.class.php(2484): convert->index('restore') #31 /apps/zentao/framework/router.class.php(775): baseRouter->loadModule() #32 /apps/zentao/www/index.php(85): router->loadModule() #33 {main} thrown in/apps/zentao/extension/custom/admin/ext/lang/zh-cn/ai.php on line3