[React] index.js:1375 Warning: The tag <plus> is unrecognized in this browser. If you meant to render a React component, start its name with an uppercase letter.

자식컴포넌트를 import할때 

import plus from './plus';

위처럼 해서

<plus value='123'></plus>

위와같이 할경우 에러 발생

import Plus from './plus';

<Plus value='123'></Plus>

위와 같이 해야 정상 동작