**Do you want to request a *feature* or report a *bug*?** bug **What is the current behavior?** visiting https://facebook.github.io/react/docs/error-decoder.html?invariant=149 does not show the error message **If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem via https://jsfiddle.net or similar (template: https://jsfiddle.net/ebsrpraL/).** **What is the expected behavior?** **Which versions of React, and which browser / OS are affected by this issue? Did this work in previous versions of React?** MacOS 10.13 / Chrome 61