ID 519078 - Crash when adding a Merge Meshes operator to a new mesh item inside specific scene files.

Problem summary
Adding a Merge Meshes operator to a new Mesh item in the Mesh Operator viewports results in a crash.
 
Customer reported version
modo.16.0v3
 
Customer reported platform
windows10
 
Steps to reproduce
 
1) Download and open the customer provided scene files.

2) Press "N" to create a new mesh item and select this item inside of the Item List.

3) Open the Mesh Operations Viewport at the top right side of the viewport:

 
4) Select the new mesh item and add the Merge Meshes operator.

 
Expected behaviour
The Merge Meshes operator should be added to the mesh item.
 
Actual behaviour
Modo crashes.
 
Workaround
Unknown.
 
Reproduced by support
 
This bug has been reproduced in:
16.0v3 - Windows 10, macOS 11.6
16.0v1 - Windows 10, macOS 11.6
 
Earliest version tested
16.0v1 - These steps did not produce the crash on earlier versions as the file crashed on opening, so unable to test further back.