Function onlyChild

docs/external/js/react.development.js:1334–1342

* Returns the first child in a collection of children and verifies that there * is only one child in the collection. * * See https://reactjs.org/docs/react-api.html#reactchildrenonly * * The current implementation of this function assumes that a single child gets * passed without a

(children)

  function onlyChild(children) {
    if (!isValidElement(children)) {
      {
        throw Error( "React.Children.only expected to receive a single React element child." );
      }
    }

    return children;
  }

  function createContext(defaultValue, calculateChangedBits) {
    if (calculateChangedBits === undefined) {