Fix state switching auto-update/manual refresh.

cmd/mtwebmapper/web/js/auto-update.js

@@ -39,8 +39,9 @@ L.Control.AutoUpdate = L.Control.extend({
 
     stopUpdate: function() {
         if (this.socket) {
-            this.socket.close();
+            var s = this.socket;
             this.socket = null;
+            s.close();
         }
     },
 
@@ -53,7 +54,9 @@ L.Control.AutoUpdate = L.Control.extend({
             me.switchButtons();
         };
 
-        this.socket.onclose = this.socket.onerror;
+        this.socket.onclose = function(evt) {
+            this.socket = null;
+        }
 
         this.socket.onopen = function(evt) {
             // Sending pings every 5 secs to keep connection alive.