"React.createElement: type is invalid" warning in IE11 when using React.Fragment

[XaveScor]

https://codesandbox.io/embed/j30o67kpxy
React shows warning in console if I use React.Fragment

Warning: React.createElement: type is invalid -- expected a string (for built-in components) or a class/function (for composite components) but got: object.

[gaearon]

Yeah, this is a false positive warning. It only appears if you use a Symbol polyfill.

I think it happens because we validate types here:

react/packages/react/src/ReactElementValidator.js

Lines 273 to 277 in 8ce5367

	const validType =
	typeof type === 'string' ||
	typeof type === 'function' ||
	typeof type === 'symbol' ||
	typeof type === 'number';

React.Fragment is a symbol. However, if Symbol is polyfilled, then its typeof won't be 'symbol'—it will be just 'object'. So this condition won't be true.

To get around this, I think we should compare type directly to React.Fragment before concluding it's invalid.

[AyWa]

I would like to work on it, if it is possible :)

[gaearon]

Sure, it's yours.

[gaearon]

@AyWa We didn't get a PR, so the submitter has fixed the issue.

[AyWa]

@gaearon Yeah I saw yesterday that the PR was already made. Sadly I planed to work on it this week.
Anyway I hope I can find a good first issue soon ;)

[dereklieu]

Glad this is fixed. Any way this can make it into a release soon?