bug fix: crashes when switching topics with open <InfoView>

index.html

@@ -2501,6 +2501,7 @@
     var InfoView = React.createClass({
       getInitialState: function() {
         return {
+          topic: null,
           owner: false,
           admin: false,
           sharer: false,
@@ -2539,6 +2540,7 @@
           return;
         }
 
+        if (this.previousMetaDesc != topic.onMetaDesc) {
           this.previousMetaDesc = topic.onMetaDesc;
           topic.onMetaDesc = this.onMetaDesc;
 
@@ -2551,12 +2553,10 @@
           } else {
             this.previousTagsUpdated = undefined;
           }
+        }
 
-        this.resetInfoView(topic, props, true);
+        if (this.state.topic != props.topic) {
-      },
+          this.setState({topic: props.topic});
-
-      resetInfoView: function(topic, props, forced) {
-        if (forced || this.props.topic != props.topic) {
           this.resetDesc(topic, props);
           this.resetSubs(topic, props);
 
@@ -2571,17 +2571,14 @@
         if (!topic) {
           return;
         }
+        this.setState({topic: null});
         topic.onMetaDesc = this.previousMetaDesc;
         topic.onSubsUpdated = this.previousSubsUpdated;
         topic.onTagsUpdated = this.previousTagsUpdated;
       },
 
       componentWillReceiveProps: function(nextProps) {
-        var topic = Tinode.getTopic(nextProps.topic);
+        this.initInfoView(nextProps);
-        if (!topic) {
-          return;
-        }
-        this.resetInfoView(topic, nextProps);
       },
 
       resetSubs: function(topic, props) {