fix(theme): ignore inner-page items in next/prev link (#3663)

Co-authored-by: Divyansh Singh <40380293+brc-dd@users.noreply.github.com>

Author: chgeo

src/client/theme-default/composables/prev-next.ts

@@ -8,7 +8,10 @@ export function usePrevNext() {
 
   return computed(() => {
     const sidebar = getSidebar(theme.value.sidebar, page.value.relativePath)
-    const candidates = getFlatSideBarLinks(sidebar)
+    const links = getFlatSideBarLinks(sidebar)
+
+    // ignore inner-page links with hashes
+    const candidates = uniqBy(links, (link) => link.link.replace(/[?#].*$/, ''))
 
     const index = candidates.findIndex((link) => {
       return isActive(page.value.relativePath, link.link)
@@ -61,3 +64,11 @@ export function usePrevNext() {
     }
   })
 }
+
+function uniqBy<T>(array: T[], keyFn: (item: T) => any): T[] {
+  const seen = new Set()
+  return array.filter((item) => {
+    const k = keyFn(item)
+    return seen.has(k) ? false : seen.add(k)
+  })
+}