SAXException while parsing input stream error

[ecuriotto]

Describe the bug

I'm trying converting the ca020 BPMN training exercises solutions, and some of them throw these exception while converting through the webapp. (Both check and convert and download button trigger the error) No error messages are shown in the webapp, only in the browser developer's tools console, and backend.
Would be nice to bring the error to the frontend more nicely
Example of exercises: 11-invoice-receipt-03.bpmn, 13-bank-robbery-big-boss.bpmn

Steps to reproduce

• run the webapp from docker
• upload the exercise file
• click on the check button
• Example of error for 11-invoice-receipt-03.bpmn: org.xml.sax.SAXException: Error: URI=null Line=198: cvc-complex-type.2.4.b: The content of element 'bpmn:dataOutputAssociation' is not complete. One of '{"http://www.omg.org/spec/BPMN/20100524/MODEL":documentation, "http://www.omg.org/spec/BPMN/20100524/MODEL":extensionElements, "http://www.omg.org/spec/BPMN/20100524/MODEL":sourceRef, "http://www.omg.org/spec/BPMN/20100524/MODEL":targetRef}' is expected.

Expected Behaviour

I would like to see a popup on the webapp with an error explanation

Library version

latest from docker

Camunda Platform 7 version

7.19.0

Camunda Platform 8 version

latest