React應用裡Invalid hook call錯誤訊息的處理

今天我做React開發時，遇到如下的錯誤訊息：

> Error: Invalid hook call. Hooks can only be called inside of the body of a function component. This could happen for one of the following reasons:

1. You might have mismatching versions of React and the renderer (such as React DOM)

2. You might be breaking the Rules of Hooks

3. You might have more than one copy of React in the same app

See  https:// fb.me/react-invalid-hoo k-call  for tips about how to debug and fix this problem.

這個錯誤輸出已經提醒了我，出錯誤的程式碼在我的應用程式MyApp.jsx裡：

原來是我這段const變數初始化程式碼寫到function外部了：

將其移至內部後錯誤消失：