java.lang.NullPointerException
   at org.netbeans.modules.db.explorer.TableExtendedDelete$1.run(TableExtendedDelete.java:113)
   at org.netbeans.modules.db.explorer.TableExtendedDelete$1.run(TableExtendedDelete.java:107)
   at org.netbeans.modules.db.metadata.model.JDBCConnMetadataModel.runReadAction(JDBCConnMetadataModel.java:97)
   at org.netbeans.modules.db.metadata.model.api.MetadataModel.runReadAction(MetadataModel.java:92)
   at org.netbeans.modules.db.explorer.TableExtendedDelete.getTopologicalSort(TableExtendedDelete.java:106)
   at org.netbeans.modules.db.explorer.TableExtendedDelete.delete(TableExtendedDelete.java:187)
   at org.netbeans.modules.db.explorer.DbExtendedDelete.delete(DbExtendedDelete.java:89)
   at org.netbeans.modules.openide.explorer.ExplorerActionsImpl$DeleteActionPerformer.actionPerformed(ExplorerActionsImpl.java:698)
   at org.openide.util.actions.ActionInvoker$1.run(ActionInvoker.java:93)
   at org.openide.util.actions.ActionInvoker$ActionRunnable.actionPerformed(ActionInvoker.java:162)
   at org.netbeans.core.ModuleActions.invokeAction(ModuleActions.java:109)
   at org.netbeans.modules.openide.actions.ActionsBridgeImpl.invokeAction(ActionsBridgeImpl.java:60)
   at org.openide.util.actions.ActionInvoker$ActionRunnable.doRun(ActionInvoker.java:153)
   at org.openide.util.actions.ActionInvoker$2.run(ActionInvoker.java:110)
   at org.openide.util.RequestProcessor$Task.run(RequestProcessor.java:1443)
   at org.netbeans.modules.openide.util.GlobalLookup.execute(GlobalLookup.java:68)
   at org.openide.util.lookup.Lookups.executeWith(Lookups.java:303)
   at org.openide.util.RequestProcessor$Processor.run(RequestProcessor.java:2058)