Just about every time I set up a new `Context.Provider`, I end up accidentally specifying a `values` prop rather than `value`.  While it's a minor error, generally I build the container in which the provider resides and commit it to the code base before I ever use it.  It's only later when I go to use it that I realize I did it again.  Since the `Context.Provider` seems pretty much useless without a `value` prop specified, I'd love it if there was a prop error if it is missing... especially if another prop is defined on the `Context.Provider` instead.
render() {
        return this.props.useDiv ? <div ref="foo" /> : <span ref="foo" />;
      }
    }
    const inst = ReactTestRenderer.create(<Foo useDiv={true} />, {
      createNodeMock,
    });
    inst.update(<Foo useDiv={false} />);
    expect(log).toEqual(['div', 'span']);
  });
  it('supports error boundaries', () => {
    const log = [];
    class Angry extends React.Component {