createGlobalState could not share state in the child mount/unmount component.

[nghiepdev]

What is the current behavior?
When the child component unmount global state is lost.

Steps to reproduce it and if possible a minimal demo of the problem
https://codesandbox.io/s/bug-react-use-create-global-state-9tykc

1. Click the plus button
2. Click the toggle button
3. Click the plus button

What is the expected behavior?
The child component should share the same state.

A little about versions:

• OS: OSX
• Browser (vendor and version): Chrome
• React: 16.13.1
• react-use: 15.1.1

[MrHuangJser]

em... I saw your example , you use the setValue like this setValue(val=>newVal), the current version does not support this approach, you can use like this

`
const [value,setValue] = useGlobalValue();
setValue(value+1)
`

[MrHuangJser]

i'll support in next pr

[nspaeth]

Can you see if #1021 fixes this?