Three points from discussion in https://github.com/reactjs/react-redux/issues/756:

* Due to https://bugs.chromium.org/p/chromium/issues/detail?id=701371, environments like CodeSandbox show `Error: null` in our “React caught an error” warning. Let’s consider skipping both as they’re not very useful and look like a bug. `Error: null` looks like a separate error and draws attention away from the real error just above.

* In any case we should probably not print `The error was thrown at:` if we don’t have a JS stack.

* There is a related issue. What do we pass to error boundary if we caught `null`? It seems that most error boundaries will intuitively do something like `if (this.state.error)` or read `error.message`, which `null` will break. There are other falsy values too like `''` and `undefined`. My proposal is we always wrap primitives into our own `Error` objects that we pass to the boundary.
this.setState({error});
      }
      render() {
        return (
          <Provider message="b">
            <Provider message="c">
              <Provider message="d">
                <Provider message="e">
                  {!this.state.error && <BadRender />}
                </Provider>
              </Provider>
            </Provider>
          </Provider>
        );
      }
    }
    ReactNoop.render(
      <Provider message="a">
        <Boundary />
        <Connector />
      </Provider>,
    );
    ReactNoop.flush();
    
    expect(ReactNoop.getChildren()).toEqual([span('a')]);
  });
  it('catches reconciler errors in a boundary during mounting', () => {
    spyOn(console, 'error');
    class ErrorBoundary extends React.Component {