java.lang.AssertionError
   at org.netbeans.modules.extbrowser.plugins.chrome.WebKitDebuggingTransport.sendCommand(WebKitDebuggingTransport.java:61)
   at org.netbeans.modules.web.webkit.debugging.TransportHelper.sendCommand(TransportHelper.java:82)
   at org.netbeans.modules.web.webkit.debugging.api.Debugger.disable(Debugger.java:93)
   at org.netbeans.modules.extbrowser.plugins.ExternalBrowserPlugin$BrowserTabDescriptor.deinitialize(ExternalBrowserPlugin.java:601)
   at org.netbeans.modules.extbrowser.plugins.ExternalBrowserPlugin$BrowserTabDescriptor.access$400(ExternalBrowserPlugin.java:492)
   at org.netbeans.modules.extbrowser.plugins.ExternalBrowserPlugin$BrowserPluginHandler.handleClose(ExternalBrowserPlugin.java:342)
   at org.netbeans.modules.extbrowser.plugins.ExternalBrowserPlugin$BrowserPluginHandler.read(ExternalBrowserPlugin.java:234)
   at org.netbeans.modules.netserver.websocket.WebSocketHandler7.readData(WebSocketHandler7.java:277)
   at org.netbeans.modules.netserver.websocket.WebSocketHandler7.readFinalFrame(WebSocketHandler7.java:229)
   at org.netbeans.modules.netserver.websocket.WebSocketHandler7.read(WebSocketHandler7.java:152)
   at org.netbeans.modules.netserver.websocket.WebSocketServer$WebSocketHandler.read(WebSocketServer.java:207)
   at org.netbeans.modules.netserver.SocketServer.readData(SocketServer.java:195)
   at org.netbeans.modules.netserver.SocketServer.run(SocketServer.java:114)
   at java.lang.Thread.run(Thread.java:662)