Don't run nil funcs from magic map

template.go

@@ -401,7 +401,7 @@ var VariablesMap map[string]bool = map[string]bool{
 func (a *Article) renderTemplateMagic(name string, params map[string]string) string {
 	renderer, ok := MagicMap[name]
 	text := ""
-	if ok {
+	if ok && renderer != nil {
 		text = renderer(name, params)
 	}
 

template_test.go

@@ -54,3 +54,18 @@ func TestMagicMap(t *testing.T) {
 		t.Error("Error in magic map ", l)
 	}
 }
+
+func TestNilFunc(t *testing.T) {
+	mw := "{{DISPLAYTITLE}}"
+	t.Log(mw)
+
+	a, err := ParseArticle("Test", mw, &DummyPageGetter{})
+	if err != nil {
+		t.Error("Error:", err)
+	}
+
+	l := a.GetText()
+	if strings.TrimSpace(l) != "" {
+		t.Error("NIL entry in magic map not caught", l)
+	}
+}