Code Splitting problem when building

[gadget-man]

When running npm start on my dev container, rather than a single .js file being created in the dist folder, I get three files, exactly as described #57

This is also an issue when trying to push the release - GitHub only creates the boilerplate-card.js file, which simply references one of the other files that is then missing from the release.

[gadget-man]

Strangely, I reverted to my previous commit and tested again and it worked fine (as expected). I then gradually added the changes, incrementally checking the build at each stage and by the time I'd got to the end, it was still building as a single file. Odd.