fix: hide epoch date when contributors missing

getAppPageLastCommitDate reduced an empty contributors array to
new Date(0), so app pages with no contributor data rendered "Page last
update: January 1, 1970". It now returns "" for empty input, and
getAppPageContributorInfo guards the format call so the timestamp stays
empty rather than formatting an Invalid Date.

Empty is falsy, so FileContributors hides the "last update" line via its
existing guard, and the page JSON-LD emits an empty dateModified instead
of the epoch. Returning "" keeps the type string, avoiding a change
across the ~15 consumers that type the field as string.

The data-side root cause (the fetcher writing empty arrays on GitHub
secondary rate limits) was fixed in #18073; this is the UI-side
defensive complement and supersedes #18071.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Co-Authored-By: wackerow <54227730+wackerow@users.noreply.github.com>

Author: 3 people

src/lib/utils/contributors.ts

@@ -63,7 +63,11 @@ export const getAppPageContributorInfo = async (
   )
 
   const latestCommitDate = getAppPageLastCommitDate(gitHubContributors)
-  const lastEditLocaleTimestamp = getLocaleTimestamp(locale, latestCommitDate)
+  // Guard the empty sentinel: getLocaleTimestamp(locale, "") would format an
+  // Invalid Date, so keep the timestamp empty when there is no commit date.
+  const lastEditLocaleTimestamp = latestCommitDate
+    ? getLocaleTimestamp(locale, latestCommitDate)
+    : ""
 
   // if (
   //   (!uniqueGitHubContributors.length || !lastEditLocaleTimestamp) &&

src/lib/utils/gh.ts

@@ -1,14 +1,19 @@
 import type { FileContributor } from "../types"
 
+// Returns "" (not the Unix epoch) for an empty array, so callers can hide
+// the "last update" line instead of formatting "January 1, 1970".
 export const getAppPageLastCommitDate = (
   gitHubContributors: FileContributor[]
-) =>
-  gitHubContributors
+): string => {
+  if (!gitHubContributors.length) return ""
+
+  return gitHubContributors
     .reduce((latest, contributor) => {
       const commitDate = new Date(contributor.date)
       return commitDate > latest ? commitDate : latest
     }, new Date(0))
     .toString()
+}
 
 const LABELS_TO_SEARCH = [
   "content",