1 files changed, 8 insertions, 3 deletions
diff --git a/src/com/vaadin/terminal/gwt/client/ApplicationConnection.java b/src/com/vaadin/terminal/gwt/client/ApplicationConnection.java
index 7d11c6245a..f0470c8ee8 100644
--- a/src/com/vaadin/terminal/gwt/client/ApplicationConnection.java
+++ b/src/com/vaadin/terminal/gwt/client/ApplicationConnection.java
@@ -40,7 +40,7 @@ import com.google.gwt.user.client.Timer;
 import com.google.gwt.user.client.ui.HasWidgets;
 import com.google.gwt.user.client.ui.Widget;
 import com.vaadin.terminal.gwt.client.ApplicationConfiguration.ErrorMessage;
-import com.vaadin.terminal.gwt.client.communication.HasJavascriptConnectorHelper;
+import com.vaadin.terminal.gwt.client.communication.HasJavaScriptConnectorHelper;
 import com.vaadin.terminal.gwt.client.communication.JsonDecoder;
 import com.vaadin.terminal.gwt.client.communication.JsonEncoder;
 import com.vaadin.terminal.gwt.client.communication.MethodInvocation;
@@ -50,6 +50,7 @@ import com.vaadin.terminal.gwt.client.communication.SharedState;
 import com.vaadin.terminal.gwt.client.communication.StateChangeEvent;
 import com.vaadin.terminal.gwt.client.communication.Type;
 import com.vaadin.terminal.gwt.client.communication.UidlValue;
+import com.vaadin.terminal.gwt.client.extensions.AbstractExtensionConnector;
 import com.vaadin.terminal.gwt.client.ui.AbstractComponentConnector;
 import com.vaadin.terminal.gwt.client.ui.VContextMenu;
 import com.vaadin.terminal.gwt.client.ui.dd.VDragAndDropManager;
@@ -1442,8 +1443,8 @@ public class ApplicationConnection {
                             JSONObject stateJson = new JSONObject(
                                     states.getJavaScriptObject(connectorId));
 
-                            if (connector instanceof HasJavascriptConnectorHelper) {
-                                ((HasJavascriptConnectorHelper) connector)
+                            if (connector instanceof HasJavaScriptConnectorHelper) {
+                                ((HasJavaScriptConnectorHelper) connector)
                                         .getJavascriptConnectorHelper()
                                         .setNativeState(
                                                 stateJson.getJavaScriptObject());
@@ -1518,6 +1519,10 @@ public class ApplicationConnection {
                             if (childConnector instanceof ComponentConnector) {
                                 newComponents
                                         .add((ComponentConnector) childConnector);
+                            } else if (!(childConnector instanceof AbstractExtensionConnector)) {
+                                throw new IllegalStateException(
+                                        Util.getConnectorString(childConnector)
+                                                + " is not a ComponentConnector nor an AbstractExtensionConnector");
                             }
                             if (childConnector.getParent() != parentConnector) {
                                 // Avoid extra calls to setParent