colouring-montreal/app/src/frontend/error-box.js

import React, { Fragment } from 'react';

function ErrorBox(props){
    if (props.msg) {
        console.error(props.msg);
    }
    return (
        <Fragment>
            {
                (props.msg)?
                (
                    <div className="alert alert-danger" role="alert">
                        {
                            (typeof props.msg === 'string' || props.msg instanceof String)?
                            props.msg
                            : 'Unexpected error'
                        }
                    </div>
                ) : null
            }
        </Fragment>
    );
}

export default ErrorBox;