Fix site.Taxonomies for taxonomies with space in name

Fixes #12001

hugolib/content_map_page.go

@@ -1859,13 +1859,12 @@ func (m *pageMap) CreateSiteTaxonomies(ctx context.Context) error {
 			LockType: doctree.LockTypeRead,
 			Handle: func(s string, n contentNodeI, match doctree.DimensionFlag) (bool, error) {
 				p := n.(*pageState)
-				plural := p.Section()
 
 				switch p.Kind() {
 				case kinds.KindTerm:
-					taxonomy := m.s.taxonomies[plural]
+					taxonomy := m.s.taxonomies[viewName.plural]
 					if taxonomy == nil {
-						return true, fmt.Errorf("missing taxonomy: %s", plural)
+						return true, fmt.Errorf("missing taxonomy: %s", viewName.plural)
 					}
 					k := strings.ToLower(p.m.term)
 					err := m.treeTaxonomyEntries.WalkPrefix(

hugolib/taxonomy_test.go

@@ -753,3 +753,26 @@ Single.
 `
 	Test(t, files)
 }
+
+func TestTaxonomiesSpaceInName(t *testing.T) {
+	t.Parallel()
+
+	files := `
+-- hugo.toml --
+[taxonomies]
+authors = 'book authors'
+-- content/p1.md --
+---
+title: Good Omens
+book authors:
+  - Neil Gaiman
+  - Terry Pratchett
+---
+-- layouts/index.html --
+{{- $taxonomy := "book authors" }}
+Len Book Authors: {{ len (index .Site.Taxonomies $taxonomy) }}
+`
+	b := Test(t, files)
+
+	b.AssertFileContent("public/index.html", "Len Book Authors: 2")
+}