XMI export of project with disconnected relations crashes (#9)

Project created in version 4.104, because in version 5.01 I can`t choose class for object in object diagramm. After several save/load in version 4.104 all diagrams "have frozen" - pressing by a mouse didn't make objects active. Then I have downloaded version 5.02 and project has revived.

Also, in this project try to export in XMI causes an error message:"System.NullReferenceException: В экземпляре объекта не задана ссылка на объект.

в SoftwareIdeasModeler.Core.Exporting.Xmi.XmiExporter21.WriteOwnedEnd(XmlTextWriter xw, AbstractDiagramItem abstractDiagramItem, UmlAssociationRole role)

в SoftwareIdeasModeler.Core.Exporting.Xmi.XmiExporter21.WriteAssociation(XmlTextWriter xw, UmlAssociation umlAssociation)

в SoftwareIdeasModeler.Core.Exporting.Xmi.XmiExporter21.WriteElement(XmlTextWriter xw, AbstractDiagramItem elem)

в SoftwareIdeasModeler.Core.Exporting.Xmi.XmiExporter21.WriteDiagram(XmlTextWriter xw, Diagram diagram)

в SoftwareIdeasModeler.Core.Exporting.Xmi.XmiExporter21.WriteModel(XmlTextWriter xw, Model model)

в SoftwareIdeasModeler.Core.Exporting.Xmi.XmiExporter21.WriteModels(XmlTextWriter xw, List`1 models)

в SoftwareIdeasModeler.Core.Exporting.Xmi.XmiExporter21.ExportToFile(String filename)

в SoftwareIdeasModeler.MainForm.xmiToolStripMenuItem_Click(Object sender, EventArgs e)

в System.Windows.Forms.ToolStripItem.RaiseEvent(Object key, EventArgs e)

в System.Windows.Forms.ToolStripMenuItem.OnClick(EventArgs e)

в System.Windows.Forms.ToolStripItem.HandleClick(EventArgs e)

в System.Windows.Forms.ToolStripItem.HandleMouseUp(MouseEventArgs e)

в System.Windows.Forms.ToolStripItem.FireEventInteractive(EventArgs e, ToolStripItemEventType met)

в System.Windows.Forms.ToolStripItem.FireEvent(EventArgs e, ToolStripItemEventType met)

в System.Windows.Forms.ToolStrip.OnMouseUp(MouseEventArgs mea)

в System.Windows.Forms.ToolStripDropDown.OnMouseUp(MouseEventArgs mea)

в System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)

в System.Windows.Forms.Control.WndProc(Message& m)

в System.Windows.Forms.ScrollableControl.WndProc(Message& m)

в System.Windows.Forms.ToolStrip.WndProc(Message& m)

в System.Windows.Forms.ToolStripDropDown.WndProc(Message& m)

в System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)

в System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)

в System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)"