The default behaviour of ctrl+click, shift+click, cmd+click (on macOS) and middle-click when clicking on links is to open the link in a new tab (or new window in the case of shift).
This behaviour is sometimes broken by careless developers.
This add-on restores the default behaviour, ensuring the modifier keys always cause links to open in a new tab (or window).
Mozilla's add-on submission process requires submission of source code. It's probably an overly strict interpretation of that requirement, but I took it to mean that something like TypeScript (that neverless produces mostly readable, unobfuscated output) would require source code upload and push an add-on into the slow approval lane.
You'll notice this repo doesn't have a *.ts file in sight, and yet achieves a very high type coverage score courtesy of JSDoc types.
I took this as an opportunity to see how far I could push this given the no *.ts constraint.