ID 562670 - Brush strokes in a RotoPaint node crash Nuke if a downstream Group node doesn't have in order Input nodes

Problem summary
Brush strokes in a RotoPaint node crash Nuke if a downstream Group node doesn't have in order Input nodes
 
This seems to come group Input nodes having the number knob, without other Input nodes with the preceding number knob values
 
Customer reported version
nuke.15.0v2
 
Customer reported platform
 
Steps to reproduce
 
1) Open Nuke

2) Create CheckerBoard>RotoPaint>Merge nodes

3) Select the Merge node and Group it using Ctrl+G
 
4) Open the Group node graph (Ctrl+Enter)
 
5) Select the Input1 node and delete it
 
6) Go back to the main Node Graph and open the RotoPaint node properties
 
7) Make any brush stroke (Paint, Clone, Blur, etc), Nuke will crash
 

 
Expected behaviour
For the RotoPaint node to create a brush stroke
 
Actual behaviour
Nuke crashes
 
Workaround
Remove all hidden number knobs from the Input nodes.
 
Reproduced by support
 
This bug has been reproduced in:
Nuke 15.0v2 - Windows 10, Rocky 9.2, macOS Monterey
Nuke 10.0v1 - Windows 10, CentOS 7
 
Earliest version tested
Nuke 10.0v1 - This issue appears to be in all tested versions of the product