Add a custom loading

[OFCL08]

I suggest adding a prop for a custom loading, just like errorComponent. Or adding an "on load" function to know when the file has finished loading.

e.g. file-viewer.jsx
Add these

FileViewer.propTypes = {
  errorComponent: PropTypes.element,
  filePath: PropTypes.string.isRequired,
  fileType: PropTypes.string.isRequired,
  loadingComponent: PropTypes.element,
  onError: PropTypes.func,
  unsupportedComponent: PropTypes.element,
};

FileViewer.defaultProps = {
  errorComponent: null,
  loadingComponent: null,
  onError: () => null,
  unsupportedComponent: null,
};

e.g. loading.jsx
Could look like this

import React from 'react';

import 'styles/loading.scss';

const Loading = () => (
  <div className="loading-container">
    {props.loadingComponent
      ? <props.loadingComponent {...props} />
      : <span className="loading" />}
  </div>
);

export default Loading;