content adapter: Fix site.GetPage using the base part of the path

Fixes #12561

hugolib/content_map_page.go

@@ -932,8 +932,8 @@ func newPageMap(i int, s *Site, mcache *dynacache.Cache, pageTrees *pageTrees) *
 				LockType: doctree.LockTypeRead,
 				Handle: func(s string, n contentNodeI, match doctree.DimensionFlag) (bool, error) {
 					p := n.(*pageState)
-					if p.File() != nil {
-						add(p.File().FileInfo().Meta().PathInfo.BaseNameNoIdentifier(), p)
+					if p.PathInfo() != nil {
+						add(p.PathInfo().BaseNameNoIdentifier(), p)
 					}
 					return false, nil
 				},