bug fix: incorrect handling of empty hashpath

index.html

@@ -3883,6 +3883,9 @@
           } else {
             console.log("Unknown sidepanel view", hash.path[0]);
           }
+        } else {
+          // Empty hashpath
+          this.setState({sidePanelSelected: ''});
         }
         // Topic for MessagesView selector.
         if (hash.path.length > 1 && hash.path[1] != this.state.topicSelected) {