Feature - Show message for invalid parameters

Is your feature request related to a problem? Please describe.
Make sure the component shows a nice-looking message if the component has invalid props, which will be returned from the Github API.

Describe the solution you'd like
If the error message states that the username cannot be located, then show a message stating which user cannot be found. If other props fail, state which and explain what kind of input is expected.

首先定位 React 组件对无效 props 的处理以及 GitHub API 的错误响应。实现用于标识不可用用户名，或无效 prop 及预期输入的消息，然后验证每种无效 prop 情况都会显示相应的消息。