Updatify / React | Release notes

React

• Improve the error message when passing null or undefined to React.cloneElement. (@nicolevy in #12534)

React DOM

• Fix an IE crash in development when using <StrictMode>. (@bvaughn in #12546)
• Fix labels in User Timing measurements for new component types. (@bvaughn in #12609)
• Improve the warning about wrong component type casing. (@nicolevy in #12533)
• Improve general performance in development mode. (@gaearon in #12537)
• Improve performance of the experimental unstable_observedBits API with nesting. (@gaearon in #12543)

React Test Renderer

• Add a UMD build. (@bvaughn in #12594)