Published flow types has a few issues

## Reporting issues with Relay

__DEV__ is not defined in flow by default

$FlowFixMeProps is not defined in flow by default

```
Missing type annotation for `U`. `U` is a type parameter declared in function type [1] and was implicitly instantiated
at call of method `map` [2].

../node_modules/relay-runtime/store/RelayModernQueryExecutor.js.flow:619:12
````

```
Error --------------------------------------------------- ../node_modules/relay-runtime/store/DataChecker.js.flow:334:11

Unreachable code.

334| break;
^^^^^^
```

These are just a few I found in first 50 of 299 errors.

You can also provide a public repository with a runnable example.