I follow the guide to package the extension in this guide: https://learn.microsoft.com/en-us/microsoft-edge/extensions/guides/packaging/using-manifoldjs-to-package-extensions.
The sample extension is in download from: https://github.com/MicrosoftEdge/MicrosoftEdge-Extensions-Demos/tree/master/color_changer
I use the tool: ManifoldJS.
but the result of the target folder is empty.