return err
		}
	}
	s.stack = append(s.stack, parents...)
	return nil
}

// UnsupportedTypeError is returned when [Marshal] encounters a type
// that cannot be converted into XML.
type UnsupportedTypeError struct {
	Type reflect.Type
}

func (e *UnsupportedTypeError) Error() string {
	return "xml: unsupported type: " + e.Type.String()
}

// can marshal themselves into valid JSON.
type Marshaler interface {
	MarshalJSON() ([]byte, error)
}

// An UnsupportedTypeError is returned by [Marshal] when attempting
// to encode an unsupported value type.
type UnsupportedTypeError struct {
	Type reflect.Type
}

func (e *UnsupportedTypeError) Error() string {
	return "json: unsupported type: " + e.Type.String()
}

			continue
		}
		if err.Error() != test.Err {
			t.Errorf("#%d: marshal(%#v) = [error] %v, want %v", idx, test.Value, err, test.Err)
		}
		if test.Kind != reflect.Invalid {
			if kind := err.(*UnsupportedTypeError).Type.Kind(); kind != test.Kind {
				t.Errorf("#%d: marshal(%#v) = [error kind] %s, want %s", idx, test.Value, kind, test.Kind)
			}
		}
	}
}

		{"UnmarshalTypeError.Struct", Field, 8},
		{"UnmarshalTypeError.Type", Field, 0},
		{"UnmarshalTypeError.Value", Field, 0},
		{"Unmarshaler", Type, 0},
		{"UnsupportedTypeError", Type, 0},
		{"UnsupportedTypeError.Type", Field, 0},
		{"UnsupportedValueError", Type, 0},
		{"UnsupportedValueError.Str", Field, 0},
		{"UnsupportedValueError.Value", Field, 0},
		{"Valid", Func, 9},
	},

pkg encoding/json, type Unmarshaler interface { UnmarshalJSON }
pkg encoding/json, type Unmarshaler interface, UnmarshalJSON([]uint8) error
pkg encoding/json, type UnsupportedTypeError struct
pkg encoding/json, type UnsupportedTypeError struct, Type reflect.Type
pkg encoding/json, type UnsupportedValueError struct
pkg encoding/json, type UnsupportedValueError struct, Str string