create react context that has a validated consumer.

create-required-context.js

// create a React context Provider/Consumer pair that
// validates the consumer is rendered within a provider
function createRequiredContext(name) {
  const Context = React.createContext()

  function Consumer(props) {
    return (
      <Context.Consumer {...props}>
        {val => {
          if (!val) {
            throw new Error(
              `The ${name}Consumer must be rendered ` +
              `within a ${name}Provider and it was not`
            )
          }
          return props.children(val)
        }}
      </Context.Consumer>
    )
  }
  return { Provider: Context.Provider, Consumer }
}
// const LanguageContext = createRequiredContext('Language')
// ReactDOM.render(<LanguageContext.Consumer />, rootEl)
// ERROR: The LanguageConsumer must be rendered within a
//        LanguageProvider and it was not
//
// @kentcdodds <3