darkTheme and lightTheme not found

Bug Description
As per documentation there should be Dark and Light themes:
https://docs.uniswap.org/sdk/widgets/swap-widget#toggling-light-dark-mode

However, when using the provided example code it is not working:

ERROR in ./src/App.js 23:28-37
export 'darkTheme' (imported as 'darkTheme') was not found in '@uniswap/widgets' (possible exports: SUPPORTED_LOCALES, SwapWidget)
 @ ./src/index.js 7:0-24 11:33-36

ERROR in ./src/App.js 23:40-50
export 'lightTheme' (imported as 'lightTheme') was not found in '@uniswap/widgets' (possible exports: SUPPORTED_LOCALES, SwapWidget)
 @ ./src/index.js 7:0-24 11:33-36

My complete code:

import './App.css';
import { ethers } from "ethers";
import { darkTheme, lightTheme, Theme, SwapWidget } from '@uniswap/widgets'

const jsonRpcEndpoint = process.env.REACT_APP_RPC_ENDPOINT;
const provider = new ethers.providers.Web3Provider(window.ethereum);

let darkMode = true;

function App() {
  return (
    <div className="App">
      <header className="App-header">
        <div classname="Uniswap">
          <SwapWidget
            provider={provider}
            jsonRpcEndpoint={jsonRpcEndpoint}
            // width={360}
            theme={darkMode ? darkTheme : lightTheme}
            />
        </div>
      </header>
    </div>
  );
}

export default App;

Start by reproducing the documented example from the linked Swap Widget documentation in App.js and checking the exports available from @uniswap/widgets. Trace why darkTheme and lightTheme are absent from the package exports. Done means the documented imports build successfully and the theme example works as described.