ID 544360 - mari.nodeGraph.viewerNode() does not work in subgraphs

Problem summary
mari.nodeGraph.viewerNode() does not work in subgraphs
 
Customer reported version
Mari 6.0v2
 
Customer reported platform
Multiple
 
Steps to reproduce
1. Open a project, such as the Example Project.
 
2. Create a Group node.
 
3. Ctrl + double-click the Group node in order to enter it.
 
4. Bring the Viewer node into the Group node by selecting a node inside the Group and pressing the 1 key.
 
5. Open the Python Console palette and write the following script into the Input Pane:
 

ngPalette = mari.palettes.find("Node Graph")index = ngPalette.currentTabIndex()graph = ngPalette.nodeGraphView(index).nodeGraph()print(graph.viewerNode())

 
6. Run the script by clicking the Evaluate Input Pane button.
 
Expected behaviour
The Python Console's Output Pane should return the Viewer node, just like it does at the root level of the Node Graph, such as the following: <mari.Mari.Node object at 0x00000212AA393B08>.
 
Actual behaviour
The Python Console's Output Pane returns None.
 
Workaround
Unknown.
 
Reproduced by support
This bug has been reproduced in:
Mari 6.0v2 - Windows 10 - CentOS 7
Mari 4.8v3 - Windows 10 - CentOS 7
 
Earliest version tested
Mari 4.8v3 - This feature did not exist before this version