Countries Aren't Highlighting

Hi, your example works excellently through the link provided, however I cannot get it working in any IDE. In visual studio, the map loads perfectly but none of the highlighting occurs. It seems as if data.json is not being used at all. Any help is appreciated.

Start by comparing the working example from the provided link with the Visual Studio setup, then inspect how data.json is loaded and used. Reproduce the map with the reported IDE setup and confirm that country highlighting works rather than only the map loading.

Written by the indexing model from the issue text.