• new icons: crown, shield, tree-diagram (#2519, #2448)
• Toaster.create() throws an error if ReactDOM.render() returns null (#2523)
  • React 16 has a breaking change where ReactDOM.render() returns null if invoked within a lifecycle method, which breaks the Toaster.create() contract of returning a Toaster instance
  • we handle this by throwing an error, forcing you to refactor your usage of the Toaster to either an element ref or a singleton module