fix(cleanup): don't error out if the container is not in the body

Author: Kent C. Dodds

Diff for: src/__tests__/bugs.js

@@ -0,0 +1,10 @@
+// this is where we'll put bug reproductions/regressions
+// to make sure we never see them again
+
+import React from 'react'
+import {render, cleanup} from '../'
+
+test('cleanup does not error when an element is not a child', () => {
+  render(<div />, {container: document.createElement('div')})
+  cleanup()
+})

Diff for: src/index.js

@@ -37,7 +37,9 @@ function cleanup() {
 // maybe one day we'll expose this (perhaps even as a utility returned by render).
 // but let's wait until someone asks for it.
 function cleanupAtContainer(container) {
-  document.body.removeChild(container)
+  if (container.parentNode === document.body) {
+    document.body.removeChild(container)
+  }
   ReactDOM.unmountComponentAtNode(container)
   mountedContainers.delete(container)
 }