fix(react-router): Allow string and object refs in withRouter

[eps1lon]

Doesn't warn about createRef or useRef values in wrappedComponentRef

[timdorr]

We could go to the level that Link does its check too: https://github.com/ReactTraining/react-router/blob/8ee6c566271f25e6956fd8ba1af85bc850417e3e/packages/react-router-dom/modules/Link.js#L63-L68

[eps1lon]

Right you still support string refs. I'm not familiar with those. Do they even work when forwarded?

I'm not sure I agree with the shape definition here. TL;DR; react already warns if the shape is bad:

Warning: Unexpected ref object provided for div. Use either a ref-setter function or React.createRef().

The wrapped component is most likely not a host component. It might be a ref forwarding component that results in the ref being attached to a host component but that's again not guaranteed. PropTypes.shape({ current: PropTypes.any }) should report no false positives. However, I don't really understand why you check for the current value. It won't be read as far as I can tell. It's probably intended to catch changes in the type? I don't think that's a helpful assumption.

[eps1lon]

Updated to allow string refs. Still think the shape check is unnecessary since react already warns about this.

@timdorr Anything left to do?

[timdorr]

Nope, looks good. Thanks!