If you’re working with React, you might run into one or both of these errors:
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 of `SomeComponent`. bundle.js%20line%20242%20%3E%20eval:45:9
Error: Element type is invalid: expected a string (for built-in components) or a class/function (for composite components) but got: object. Check the render method of `SomeComponent`.
One possible problem, which is what happened to me, is that you simply forgot to export one of your modules. In this case, I had a child component which I forgot to export, but the resulting error said nothing about the child component so it took awhile to puzzle this out. Hopefully this helps someone else figure out the problem faster than I!