message: Fix backdrop panel empty image
diff: @@ -140,12 +140,13 @@ export default class BackdropPanel extends React.PureComponent<IProps, IState> {
  public render() {
  if (!this.props.backgroundImage) return null;
  return <div className="mx_BackdropPanel">
  - <img
  + { this.state?.llpImage !== 'data:,' && <img
  className="mx_BackdropPanel--canvas"
  - src={this.state.llpImage} />
  - <img
  + src={this.state.llpImage} /> }
  +
  + { this.state?.lpImage !== 'data:,' && <img
  className="mx_BackdropPanel--canvas"
  - src={this.state.lpImage} />
  + src={this.state.lpImage} /> }
  <canvas
  ref={this.leftLeftPanelRef}
  className="mx_BackdropPanel--canvas"
  