java.lang.NullPointerException
        at org.netbeans.modules.python.project.ui.actions.CleanBuildCommand.invokeAction(CleanBuildCommand.java:150)
        at org.netbeans.modules.python.project.PythonActionProvider$1.run(PythonActionProvider.java:92)
        at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:576)
        at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:1013)