未捕获的TypeError：this._propertySetter不是函数

Question

我正在尝试使用Polymer构建我的个人网站，突然间出现了这些错误。

如果您知道解决方案，请帮助我。

感谢。

> Uncaught TypeError: this._propertySetter is not a function app-route.html:398
>     at HTMLElement.__setMulti (app-route.html:398)
>     at HTMLElement.__tryToMatch (app-route.html:324)
>     at Object.runMethodEffect [as fn] (property-effects.html:772)
>     at runEffectsForProperty (property-effects.html:137)
>     at runEffects (property-effects.html:103)
>     at HTMLElement._propertiesChanged (property-effects.html:1533)
>     at HTMLElement._flushProperties (property-accessors.html:496)
>     at HTMLElement._flushClients (property-effects.html:1442)
>     at HTMLElement._propertiesChanged (property-effects.html:1529)
>     at HTMLElement._flushProperties (property-accessors.html:496)