_.jsx

useEffect(() => {
  setHasError(false)
  if (!editMode) {
    import(`../content/${slug}.json`)
      .then((content) => {
        setContent(content.default)
      })
      .catch((e) => {
        setHasError(true)
      })
  } else {
    // TODO now we're loading this data 2x when in edit mode
    loadData().then((result) => {
      if (result && result.error) {
        setHasError(true)
      }
    })
  }
}, [slug, setContent, setHasError, editMode])

if (hasError) {
  return <NotFound />
}

//... return page component