Maybe a documentation issue or an issue with https://github.com/arittner/WLED/blob/main/.vscode/tasks.json
The documentation describes, I can run a build (with the checkmark symbol), but the Build is not working for me. VS Code shows only the Command Palette with PlatformIO: Build and I cannot trigger the command. If I remove PlatformIO: , I see this task list:

All three tasks correspond to the tasks.json and only Build: binary only is working. For HTML builds, I need a NPM installation. It would be useful to link to https://kno.wled.ge/advanced/custom-features/#changing-web-ui to give more hints, how to compile with HTML and how to prepare the environment. And maybe also Custom Features with chapter Changing Web UI should be updated.
VS Code: 1.81.1
OS: Windows 11 x64
PlatformIO: v3.3.1