We will render the background image URL in an img element at the very top to show users the image they added as the game world image URL.
mern-vrgame/client/game/GameForm.js:
<img src={this.state.game.world}/><TextField id="world" label="Game World Equirectangular Image (URL)" value={this.state.game.world} onChange={this.handleChange('world')}/>