Last update of VSCode (1.78.1+) improved security over UNC paths, then if you try to access UNC paths without first explicitly allowing them on settings you will get this error:

So if you have private extensions on a network folder, you will see that error.
Don't know where the "Cannot read properties of undefined" is propagating from, could be possibile I will personally investigate later this week and PR something.
Source: https://code.visualstudio.com/docs/setup/windows#_working-with-unc-paths\
Last update of VSCode (1.78.1+) improved security over UNC paths, then if you try to access UNC paths without first explicitly allowing them on settings you will get this error:
So if you have private extensions on a network folder, you will see that error.
Don't know where the "Cannot read properties of undefined" is propagating from, could be possibile I will personally investigate later this week and PR something.
Source: https://code.visualstudio.com/docs/setup/windows#_working-with-unc-paths\