Failure to add mappings through the settings UI

On the Git Project Settings, if I remove all the existing mappings, I am no longer able to add a new mapping by clicking the + sign. An error is logged in the browser console:
```
Uncaught TypeError: newEntry.children().children(...).children()[0] is undefined
```
The workaround is to run ##class(SourceControl.Git.API).Configure() in IRIS terminal to get back the default mappings.