Don't barf if we we can't get a given room ID

src/controllers/organisms/MemberList.js

@@ -113,7 +113,9 @@ module.exports = {
     roomMembers: function(limit) {
         if (!this.props.roomId) return {};
         var cli = MatrixClientPeg.get();
-        var all_members = cli.getRoom(this.props.roomId).currentState.members;
+        var room = cli.getRoom(this.props.roomId);
+        if (!room) return {};
+        var all_members = room.currentState.members;
         var all_user_ids = Object.keys(all_members);
 
         all_user_ids.sort(function(userIdA, userIdB) {