Before this change, `require("socket.io-client").Socket` would return
"undefined".
Note: having access to the Socket class allows users to modify its
prototype.
Related: https://github.com/socketio/socket.io/issues/3726
The syntax was invalid:
```
export const io = io;
^
SyntaxError: Identifier 'io' has already been declared
at Loader.moduleStrategy (internal/modules/esm/translators.js:122:18)
```