Warning: Cannot update a component (`ForwardRef(Field)`) while rendering a different component (`ForwardRef(Field)`)

### Are you submitting a **bug report** or a **feature request**?

Bug report

### What is the current behavior?

A react warning about "invalid set state in render" is shown when rendering the value of a conditionally rendered field that has an initialValue set.

### What is the expected behavior?

That React does not print warnings in the console.

### Sandbox Link

https://codesandbox.io/s/tender-sea-6fmu3?fontsize=14&hidenavigation=1&theme=dark

### What's your environment?

```
{
"react": 16.13.1,
"react-dom": 16.13.1,
"react-final-form": 6.5.1,
"react-scripts": 3.4.1,
"final-form": 4.20.1
}
```

### Other information

Note that the example is a bit contrived and that the real life scenario causing is a bit more complex.

This issue might be related to https://github.com/final-form/react-final-form/issues/828. That issue is regarding a FormSpy and this is related to a conditionally rendered Field with initialValue prop.

Thanks for taking the time and hope this can help in some way.