Argument of type ‘Element’ is not assignable to parameter of type ‘ReactElement

This code:

import * as React from 'react';                                                                                              
                                                                                 
const Component = () => <div/>;                                                  
                
function culprit<P>(node: React.ReactElement<P>) {
  console.log(node);
}
                                                             
culprit(<Component/>);

…produces this compilation error when compiling with TypeScript:

error TS2345: Argument of type ‘Element’ is not assignable to parameter of type ‘ReactElement’. Type ‘null’ is not assignable to type ‘ReactElement

This only happens when the strictNullChecks TypeScript compilation flag is set to true.

Yes I could disable that flag, but I want it on for added compile-time checking/safety.

If I change the last line to this:

culprit( (<Component/> as React.ReactElement<any>) );

…it works with the flag set to true.

I’ve recently tried migrating from “plain” JavaScript to TypeScript in a React project and this is tripping up all my tests, so adding all the TypeScript type assertions to all these occurrences in the test code will be a pain.

Is this a bug, or do I have no other choice?

Answer

This is apparently an issue which was introduced in the 15.0.5 React type definitions. If you change to 15.0.4, everything should be fine.

See this issue: https://github.com/DefinitelyTyped/DefinitelyTyped/pull/14284