Submit errors are not removed on `fields.remove` call

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

### What is the current behavior?

[](https://codesandbox.io/s/lxqoqzvx57)

### What is the expected behavior?
Submit error is matched with array field - when the field is removed, submit error is also removed

### What's your environment?

Forked from offical example:
```
"dependencies": {
"styled-components": "2.2.4",
"react-final-form-arrays": "1.0.0",
"react-final-form": "1.1.1",
"react-dom": "16.2.0",
"react": "16.2.0",
"final-form-arrays": "1.0.0",
"final-form": "1.2.1"
}
```
Locally:
```
"final-form": "^4.1.0",
"final-form-arrays": "^1.0.4",
...
"react-final-form": "^3.0.5",
"react-final-form-arrays": "^1.0.3",
```