ID 490652 - Nuke doesn't load the environment variable set OCIO config, if the custom OCIO config knob is pointing to a non-existent config

Problem summary
Nuke doesn't load the environment variable set OCIO config, if the custom OCIO config knob is pointing to a non-existent config

Customer reported version
13.0::13.0v4

Customer reported platform
windows10

Steps to reproduce

1) Open terminal, and set the OCIO environment variable to an existing config, like nuke-default, For example:
 
2) In the same terminal, launch Nuke.

3) Open the attached OCIOenvVarBug_goodPath.nk script, and with a valid custom OCIO config knob, it loads the OCIO environment variable set OCIO config correctly.

4) Clear the script

5) Open the attached OCIOenvVarBug_badPath.nk script, and with an invalid custom OCIO config knob, it fails to load the OCIO environment variable set OCIO config.

Expected behaviour
For the OCIO environment variable set OCIO config to be used when the custom OCIO config knob is invalid

Actual behaviour
Nuke errors, and loads the previously used OCIO config instead:

​

Workaround
Unknown.

Reproduced by support
This bug has been reproduced in:
Nuke 13.0v5 - Windows 10, CentOS 7.5, macOS Big Sur
Nuke 11.0v1 - Windows 10, CentOS 7.5,

Earliest version tested
Nuke 11.0v1 - This issue appears to be in all versions of the product