Function assertUniqueChildren

lib/create-tree.js:61–71

(page)

}

function assertUniqueChildren(page) {
  if (page.children.length !== new Set(page.children).size) {
    const count = {}
    page.children.forEach((entry) => (count[entry] = 1 + (count[entry] || 0)))
    let msg = `${page.relativePath} has duplicates in the 'children' key.`
    for (const [entry, times] of Object.entries(count)) {
      if (times > 1) msg += ` '${entry}' is repeated ${times} times. `
    }
    throw new Error(msg)
  }
}