message: Handle errors when previewing rooms more safely
  Fixes
  See for additional context.
diff: @@ -342,7 +342,7 @@ export default createReactClass({
  peekLoading: false,
  });
  this._onRoomLoaded(room);
  - }, (err) => {
  + }).catch((err) => {
  if (this.unmounted) {
  return;
  }
  @@ -355,7 +355,7 @@ export default createReactClass({
  // This won't necessarily be a MatrixError, but we duck-type
  // here and say if it's got an 'errcode' key with the right value,
  // it means we can't peek.
  - if (err.errcode == "M_GUEST_ACCESS_FORBIDDEN") {
  + if (err.errcode === "M_GUEST_ACCESS_FORBIDDEN" || err.errcode === 'M_FORBIDDEN') {
  // This is fine: the room just isn't peekable (we assume).
  this.setState({
  peekLoading: false,
  @@ -365,8 +365,6 @@ export default createReactClass({
  }
  });
  } else if (room) {
  - //viewing a previously joined room, try to lazy load members
  -
  // Stop peeking because we have joined this room previously
  MatrixClientPeg.get().stopPeeking();
  this.setState({isPeeking: false});
  