tpl: Skip dot and temp files inside /layouts

Fixes #13579

tpl/tplimpl/templatestore.go

@@ -1118,15 +1118,20 @@ func (s *TemplateStore) insertTemplates(include func(fi hugofs.FileMetaInfo) boo
 	legacyOrdinalMappings := map[legacyTargetPathIdentifiers]legacyOrdinalMappingFi{}
 
 	walker := func(pth string, fi hugofs.FileMetaInfo) error {
-		piOrig := fi.Meta().PathInfo
 		if fi.IsDir() {
 			return nil
 		}
 
+		if isDotFile(pth) || isBackupFile(pth) {
+			return nil
+		}
+
 		if !include(fi) {
 			return nil
 		}
 
+		piOrig := fi.Meta().PathInfo
+
 		// Convert any legacy value to new format.
 		fromLegacyPath := func(pi *paths.Path) *paths.Path {
 			p := pi.Path()
@@ -1922,3 +1927,11 @@ func configureSiteStorage(opts SiteOptions, watching bool) *storeSite {
 
 	return s
 }
+
+func isBackupFile(path string) bool {
+	return path[len(path)-1] == '~'
+}
+
+func isDotFile(path string) bool {
+	return filepath.Base(path)[0] == '.'
+}

tpl/tplimpl/templatestore_integration_test.go

@@ -973,3 +973,18 @@ s2.
 		}
 	})
 }
+
+func TestSkipDotFiles(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- hugo.toml --
+-- layouts/all.html --
+All.
+-- layouts/.DS_Store --
+{{ foo }}
+`
+
+	// Just make sure it doesn't fail.
+	hugolib.Test(t, files)
+}