Fixed socket calls.

app/assets/javascripts/editor/evaluation.js.erb

@@ -137,13 +137,13 @@ CodeOceanEditorEvaluation = {
   },
 
   killWebsocketAndContainer: function () {
-    if (this.websocket.readyState != WebSocket.OPEN) {
+    if (this.websocket.getReadyState() != WebSocket.OPEN) {
       return;
     }
 
     this.websocket.send(JSON.stringify({cmd: 'exit'}));
-    this.websocket.flush();
-    this.websocket.close();
+    this.websocket.killWebSocket();
+    
     this.hideSpinner();
     this.running = false;
     this.toggleButtonStates();

app/assets/javascripts/editor/websocket.js.erb

@@ -88,3 +88,18 @@ CommandSocket.prototype.executeCommand = function(cmd) {
 CommandSocket.prototype.send = function(data) {
   this.websocket.send(data);
 };
+
+/**
+ * Returns the ready state of the socket.
+ */
+CommandSocket.prototype.getReadyState = function() {
+  return this.websocket.readyState;
+};
+
+/**
+ * Closes the websocket.
+ */
+CommandSocket.prototype.killWebSocket = function() {
+  this.websocket.flush();
+  this.websocket.close();
+};