Why the diagram is not displayed (without errors)?

Hello, I’m trying to upload a diagram, but I am getting warnning: unresolved reference <error>. When I delete this element: <errorEventDefinition errorRef=“error”></errorEventDefinition> the warning disappears, but the diagram is not displayed and there are no errors and warnings. Here is the view:

I can’t see what is the error for not visualizing the diagram and therefore I decided to ask you for help. I’m just including my file attachment:
file20.xml (6.8 KB)

This diagram is broken. There is an event definition <errorEventDefinition errorRef="error"></errorEventDefinition> referencing an error that doesn’t exist. This is probably an issue with the tool that exported this diagram.

But the XML is generated by using flowable java library. I built org.flowable.bpmn.model.BpmnModel and after that I used org.flowable.bpmn.converter.BpmnXMLConverter#convertToXML method.

Well, then one of these tools is broken.