Fix humanize when string is empty

Fixes #2272

tpl/template_funcs.go

@@ -1703,6 +1703,11 @@ func humanize(in interface{}) (string, error) {
 	if err != nil {
 		return "", err
 	}
+
+	if word == "" {
+		return "", nil
+	}
+
 	return inflect.Humanize(word), nil
 }
 

tpl/template_funcs_test.go

@@ -1805,8 +1805,11 @@ func TestInflect(t *testing.T) {
 		expected    string
 	}{
 		{humanize, "MyCamel", "My camel"},
+		{humanize, "", ""},
 		{pluralize, "cat", "cats"},
+		{pluralize, "", ""},
 		{singularize, "cats", "cat"},
+		{singularize, "", ""},
 	} {
 
 		result, err := this.inflectFunc(this.in)