Copy + Paste and then Undo Collapsed Sub process throws JS Errors

[anandcoupa]

Describe the Bug

Copy Paste and then Undo of Collapsed Sub process throws following JS Errors
unhandled error in event listener TypeError: Cannot read properties of null (reading 'children')
related to MoveConnectionHandler.js

Steps to Reproduce

1. Create a sample BPMN consisting of a collapsed subprocess
2. Do a copy paste of the collapsed subprocess
3. Notice that the paste operation is successful and if you navigate to newly pasted node, you see the underlying elements from the copied subprocess.
4. Perform undo (cmd+z or ctrl + z)

Actual:

• Newly pasted collapsed subprocess stays as is, JS error seen in the console

Please find the attached recording

Screen.Recording.2025-01-07.at.4.36.13.PM_compressed.mp4

Expected Behavior

• No JS errors thrown
• Undo functionality works as expected.

Environment

• Browser: Chrome 129
• OS: MacOS
• Library version: v17.11.1

[abdul99ahad]

I can reproduce the error. Moving it to ready

[barmac]

I can reproduce too. This crashes the editor.

[abdul99ahad]

@jarekdanielak to have a look on this.