Fix .Fragments when called cross sites on uninitialized output format

Fixes #10794

resources/page/page.go

@@ -334,9 +334,6 @@ type PageWithoutContent interface {
 	// Used in change/dependency tracking.
 	identity.Provider
 
-	// Fragments returns the fragments for this page.
-	Fragments(context.Context) *tableofcontents.Fragments
-
 	// Headings returns the headings for this page when a filter is set.
 	// This is currently only triggered with the Related content feature
 	// and the "fragments" type of index.
@@ -407,6 +404,9 @@ type SitesProvider interface {
 type TableOfContentsProvider interface {
 	// TableOfContents returns the table of contents for the page rendered as HTML.
 	TableOfContents(context.Context) template.HTML
+
+	// Fragments returns the fragments for this page.
+	Fragments(context.Context) *tableofcontents.Fragments
 }
 
 // TranslationsProvider provides access to any translations.

resources/page/page_lazy_contentprovider.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/gohugoio/hugo/lazy"
 	"github.com/gohugoio/hugo/markup/converter"
+	"github.com/gohugoio/hugo/markup/tableofcontents"
 )
 
 // OutputFormatContentProvider represents the method set that is "outputFormat aware" and that we
@@ -73,6 +74,17 @@ func (lcp *LazyContentProvider) Reset() {
 	lcp.init.Reset()
 }
 
+func (lcp *LazyContentProvider) TableOfContents(ctx context.Context) template.HTML {
+	lcp.init.Do(ctx)
+	return lcp.cp.TableOfContents(ctx)
+
+}
+
+func (lcp *LazyContentProvider) Fragments(ctx context.Context) *tableofcontents.Fragments {
+	lcp.init.Do(ctx)
+	return lcp.cp.Fragments(ctx)
+}
+
 func (lcp *LazyContentProvider) Content(ctx context.Context) (any, error) {
 	lcp.init.Do(ctx)
 	return lcp.cp.Content(ctx)