属性值应为字符串类型,但为空

我有一个 Icon.jsx 组成部分:

import React from 'react'; import { css } from 'emotion';

import ArrowRight from "./arrow-right.svg";

export const iconTypes = {
    arrowRight: 'ARROW_RIGHT',
    //arrowLeft: "ARROW_LEFT", }

const iconSrc = {
    ARROW_RIGHT: ArrowRight,
    ARROW_LEFT: ArrowLeft, }


export default ({ type }) => {
    return (
        <Icon>
            <img src={iconSrc[type]} />
        </Icon>
    )
};

和一个`图标.jsx'故事:

import React from "react";
import { storiesOf } from "@storybook/react";
import { action } from "@storybook/addon-actions";
import Icon from "../components/Icon/Index";
import { iconTypes } from "../components/Icon/Index";


storiesOf("Icon", module)
    .add("with text", () => (
        <Icon type={iconTypes.leftArrow}>
            </Icon>
    ));

我经常在计算机上遇到以下错误 Icon.jxs

 Property value expected type of string but got null

但我想不出来,任何帮助都将不胜感激。