Another typescript 4 breaking change

gistfile1.txt

This type definition is sort of weird, but it works in typescript v3:
```ts
interface EncodedSomething<TProps, TEncoding extends BaseEncodingSomeWhere> extends BaseEncodedThingies<TProps> {
  encoding: TEncoding;
}

```

Then in use:
```ts

class EncodedSomethingUIComponent<TSomethingToBeEncoded extends EncodedSomething<{}, 
  TSomethingToBeEncoded["encoding"] // HERE IS THE ERROR: 'TSomethingToBeEncoded["encoding"]' does not satisfy the constraint 'BaseEncodingSomeWhere'.
>{
  // impl.
}
```
Don't know why this is a breaking change, can't find any where (yet).

For typescript 4. I fixed the error with `infer`.
```ts
type MyEncodingType<T> = T extends EncodedSomething<any, infer TEncoding> ? TEncoding : BaseEncodingSomeWhere;

class EncodedSomethingUIComponent<TSomethingToBeEncoded extends EncodedSomething<{}, 
  MyEncodingType<TSomethingToBeEncoded> // THE FIX.
>{
  // impl.
}
```