Groups in empty diagram cause errors

[BelindaBecker]

Describe the Bug

After adding a group to an empty diagram, the editor crashes when trying to add other elements.

Steps to Reproduce

Steps to reproduce the behavior:

on https://demo.bpmn.io/new

1. Open the empty/initial diagram
2. delete the start event
3. add a group
4. add for example a pool

Result: the console throws a lot of errors and the editor gets stuck.

Expected Behavior

It should be possible to keep on modeling.

Environment

Please complete the following information:

• Browser: Chrome 75.0.3770.142
• OS: Windows 10
• Library version: The one deployed on https://demo.bpmn.io/new, should be bpmn-js 4.0.3

[nikku]

Could you provide us with your logs, starting from the first error?

[nikku]

On my machine (Arch Linux, your Chrome version) I cannot reproduce the issue given the steps you procided:

[BelindaBecker]

Sure! This is what I get from the brwoser console:
Topmost errors in trace:

Next Error:

After this, the exactly same three errors are thrown multiple times.
I am able to reproduce this every time I do the steps describe above..

[BelindaBecker]

I did some more testing: the error occurs only if you add a pool !

[nikku]

Thanks for the additional clarification. I can reproduce it now. We will have a look. 👍

[pinussilvestrus]

Root-Cause: In CreateParticipantBehavior the childrenBBox has malformed (NaN) height and width properties, because bpmn:Group elements are ignored. If no other elements are there, of course, no children are still available to create the correct participant bounds.

I'll have a look at this next week 🎸

[pinussilvestrus]

Closed via 5d5f33c