java.lang.NullPointerException
   at org.netbeans.modules.web.webkit.debugging.api.css.SourceRange.<init>(SourceRange.java:63)
   at org.netbeans.modules.web.webkit.debugging.api.css.Property.<init>(Property.java:93)
   at org.netbeans.modules.web.webkit.debugging.api.css.Style.<init>(Style.java:80)
   at org.netbeans.modules.web.webkit.debugging.api.css.Rule.<init>(Rule.java:103)
   at org.netbeans.modules.web.webkit.debugging.api.css.StyleSheetBody.<init>(StyleSheetBody.java:74)
   at org.netbeans.modules.web.webkit.debugging.api.css.CSS.getStyleSheet(CSS.java:143)
   at org.netbeans.modules.web.inspect.webkit.WebKitPageModel$WebPaneSynchronizer.performHoverRelatedStyleSheetUpdate(WebKitPageModel.java:1030)
   at org.netbeans.modules.web.inspect.webkit.WebKitPageModel$WebPaneSynchronizer.updateSelectionMode(WebKitPageModel.java:1019)
   at org.netbeans.modules.web.inspect.webkit.WebKitPageModel$WebPaneSynchronizer.access$1900(WebKitPageModel.java:893)
   at org.netbeans.modules.web.inspect.webkit.WebKitPageModel$WebPaneSynchronizer$1.run(WebKitPageModel.java:923)
Caused: org.openide.util.RequestProcessor$SlowItem: task failed due to: java.lang.NullPointerException
   at org.openide.util.RequestProcessor.post(RequestProcessor.java:424)
   at org.netbeans.modules.web.inspect.webkit.WebKitPageModel$WebPaneSynchronizer.propertyChange(WebKitPageModel.java:899)
   at java.beans.PropertyChangeSupport.fire(PropertyChangeSupport.java:335)
   at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:327)
   at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:263)
   at org.netbeans.modules.web.inspect.PageModel.firePropertyChange(PageModel.java:213)
   at org.netbeans.modules.web.inspect.webkit.WebKitPageModel.access$1000(WebKitPageModel.java:82)
   at org.netbeans.modules.web.inspect.webkit.WebKitPageModel$DOMListener$1.run(WebKitPageModel.java:391)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1432)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2042)