React-next.js元件中[已解決]react異常：Can‘t perform a React state update on an unmounted component

報錯如下圖:

Warning: Can't perform a React state update on an unmounted component. 
This is a no-op, but it indicates a memory leak in your application. 
To fix, cancel all subscriptions and asynchronous tasks in the componentWillUnmount method.      

原因：

componentWillUnmount() {
    this.setState = ()=>false;
}