Added extra precaution to avoid null error

web/react/components/channel_header.jsx

@@ -46,6 +46,7 @@ var ExtraMembers = React.createClass({
         var data_content = "";
         var sortedMembers = this.props.members;
 
+        if(sortedMembers) {
             sortedMembers.sort(function(a,b) {
                 return a.username.localeCompare(b.username);
             })
@@ -53,6 +54,7 @@ var ExtraMembers = React.createClass({
             sortedMembers.forEach(function(m) {
                 data_content += "<div style='white-space: nowrap'>" + m.username + "</div>";
             });
+        }
 
         return (
             <div style={{"cursor" : "pointer"}} id="member_popover" data-toggle="popover" data-content={data_content} data-original-title="Members" >