language change in virtual keyboard can trigger exception

[thomaskrause]

When selecting e.g. Urdu Phonetic

Exception type: java.lang.ClassCastException
Message: elemental.json.impl.JreJsonNull cannot be cast to elemental.json.JsonString
Stacktrace: 
elemental.json.impl.JreJsonArray.getString(JreJsonArray.java:102)
annis.gui.components.VirtualKeyboardCodeEditor$UpdateLangJSFunction.call(VirtualKeyboardCodeEditor.java:105)
com.vaadin.server.JavaScriptCallbackHelper$1.call(JavaScriptCallbackHelper.java:80)
sun.reflect.GeneratedMethodAccessor904.invoke(Unknown Source)
java.lang.reflect.Method.invoke(Method.java:606)
com.vaadin.server.ServerRpcManager.applyInvocation(ServerRpcManager.java:158)
com.vaadin.server.ServerRpcManager.applyInvocation(ServerRpcManager.java:118)
com.vaadin.server.communication.ServerRpcHandler.handleInvocations(ServerRpcHandler.java:313)
com.vaadin.server.communication.ServerRpcHandler.handleRpc(ServerRpcHandler.java:202)
com.vaadin.server.communication.PushHandler$2.run(PushHandler.java:153)
com.vaadin.server.communication.PushHandler.callWithUi(PushHandler.java:232)
com.vaadin.server.communication.PushHandler.onMessage(PushHandler.java:492)
com.vaadin.server.communication.PushAtmosphereHandler.onMessage(PushAtmosphereHandler.java:88)
com.vaadin.server.communication.PushAtmosphereHandler.onRequest(PushAtmosphereHandler.java:78)
org.atmosphere.cpr.AsynchronousProcessor.action(AsynchronousProcessor.java:199)
org.atmosphere.cpr.AsynchronousProcessor.suspended(AsynchronousProcessor.java:107)
org.atmosphere.container.Servlet30CometSupport.service(Servlet30CometSupport.java:66)
org.atmosphere.cpr.AtmosphereFramework.doCometSupport(AtmosphereFramework.java:2075)
org.atmosphere.websocket.DefaultWebSocketProcessor.dispatch(DefaultWebSocketProcessor.java:571)
org.atmosphere.websocket.DefaultWebSocketProcessor$3.run(DefaultWebSocketProcessor.java:333)
org.atmosphere.util.VoidExecutorService.execute(VoidExecutorService.java:101)
org.atmosphere.websocket.DefaultWebSocketProcessor.dispatch(DefaultWebSocketProcessor.java:328)
org.atmosphere.websocket.DefaultWebSocketProcessor.invokeWebSocketProtocol(DefaultWebSocketProcessor.java:425)
org.atmosphere.container.JSR356Endpoint$1.onMessage(JSR356Endpoint.java:213)
org.atmosphere.container.JSR356Endpoint$1.onMessage(JSR356Endpoint.java:210)
org.apache.tomcat.websocket.WsFrameBase.sendMessageText(WsFrameBase.java:393)
org.apache.tomcat.websocket.WsFrameBase.processDataText(WsFrameBase.java:494)
org.apache.tomcat.websocket.WsFrameBase.processData(WsFrameBase.java:289)
org.apache.tomcat.websocket.WsFrameBase.processInputBuffer(WsFrameBase.java:130)
org.apache.tomcat.websocket.server.WsFrameServer.onDataAvailable(WsFrameServer.java:60)
org.apache.tomcat.websocket.server.WsHttpUpgradeHandler$WsReadListener.onDataAvailable(WsHttpUpgradeHandler.java:203)
org.apache.coyote.http11.upgrade.AbstractServletInputStream.onDataAvailable(AbstractServletInputStream.java:194)
org.apache.coyote.http11.upgrade.AbstractProcessor.upgradeDispatch(AbstractProcessor.java:95)
org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:653)
org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:222)
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1556)
org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1513)
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
java.lang.Thread.run(Thread.java:745)