Throw errors when I after building in webpack an run on the browser

[joket1999]

Warning: React.createElement: type should not be null, undefined, boolean, or number. It should be a string (for DOM elements) or a ReactClass (for composite components). Check the render method ofFirstModal.

Uncaught Invariant Violation: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: undefined. Check the render method ofFirstModal.

But I try import the pre-build(es5) files, and it works.

[qimingweng]

Hmm, what does your npm ls --depth=0 look like?