ID 456647 - Resizing the Node Graph map to 0 causes the nodes in the Node Graph to disappear

Problem summary
Resizing the Node Graph map to 0 causes the nodes in the Node Graph to disappear.

Customer reported version
Nuke 12.0v1

Customer reported platform
Windows 10

Steps to reproduce

1) Open Nuke.

2) Open a script, or create some nodes in the Node Graph, then zoom in on the nodes. This should make the Node Graph map appear.

3) Resize the Node Graph map, either by click and dragging its top left corner, or by running the following code in the Script Editor:

nuke.Root()['mapsize'].setValue(0)

The Node Graph map should no longer be visible.

4) Create a new node - all of the nodes should disappear in the Node Graph. Clicking on the Node Graph will then display them again.

NOTE: In some previous Nuke versions, the bug can be reproduced by simply clicking on the Node Graph, instead of creating a new node.

Expected behaviour
The Node Graph should be correctly displayed when the Node Graph map is resized to 0.

Actual behaviour
Resizing the Node Graph map to 0 causes the nodes in the Node Graph to disappear.

Workaround
To get the Node Graph map back, you can run the following code in the Script Editor:

nuke.Root()['mapsize'].setValue(0.2)

Reproduced by support

This bug has been reproduced in:
Nuke 12.2v3 - Windows 10 - Linux CentOS 7 - macOS 10.14 (Mojave)

Nuke 12.0v1 - Windows 10 - Linux CentOS 7 - macOS 10.14 (Mojave) - Regression

Unable to reproduce bug in:
Nuke 11.3v6 - Windows 10 - Linux CentOS 7 - macOS 10.14 (Mojave)

Earliest version tested
Nuke 11.3v6
- This issue doesn't appear in this version and has regressed