Check error to see if it's actually a failure to peek

src/components/structures/RoomView.js

@@ -177,11 +177,15 @@ module.exports = React.createClass({
         roomProm.then((room) => {
             this._calculatePeekRules(room);
             return this._initTimeline(this.props);
-        }).catch(() => {
+        }).catch((err) => {
+            if (err.errcode == "M_GUEST_ACCESS_FORBIDDEN") {
                 // This is fine: the room just isn't peekable (we assume).
                 this.setState({
                     timelineLoading: false,
                 });
+            } else {
+                throw err;
+            }
         }).done();
     },