:ERROR MESSAGE:

org.apache.ofbiz.widget.renderer.ScreenRenderException: Error rendering screen [component://envelopes/widget/CategoryScreens.xml#category]: java.lang.IllegalArgumentException: Error running script at location [component://envelopes/webapp/envelopes/WEB-INF/actions/category/category.groovy]: java.lang.NullPointerException: Cannot invoke method get() on null object (Error running script at location [component://envelopes/webapp/envelopes/WEB-INF/actions/category/category.groovy]: java.lang.NullPointerException: Cannot invoke method get() on null object)