Some links on the Progress Dashboard show up as `undefined`

[AaravMalani]

For example,

The link shows up as https://gitmastery.org/undefined

Reproduction

Tested on Git-Mastery v7.8.2, Git version 2.55.0.windows.3, gh version 2.97.0.

1. Complete an exercise
2. Enable remote syncing of exercises
3. Open the progress tracker and hover over the link of T1L3. Putting a Folder Under Git's Control