Remove spurious AppSubUrl in serviceworker request.

[zeripath]

There is another spurious AppSubUrl placement in the serviceworker registration.
This PR removes it.

Signed-off-by: Andrew Thornton art27@cantab.net

[silverwind]

This comment no longer matches the code, it needs to be updated

[silverwind]

Are you sure it's removable? Does it still work with the app on a subdirectory?

[silverwind]

I wonder why we actually put it on AppSubUrl in first place. The purpose of the SW is to manage assets below AssetUrlPrefix so I think the correct URL might just be ${AssetUrlPrefix}/serviceworker.js which should also work in multi-domain deployments with assets on a separate domain.

[zeripath]

I run gitea on a subdirectory as my testing platform so that's why I spot these. Removing this makes this correct for me.

I don't run with a static URL prefix so I don't know what those URLs should look like - but I doubt that they should have AppSuburl either.

It may be helpful to add comments to the static URL prefix go "constant" similar to those I added to AppURL and AppSuburl which state whether or not they have preceding or suffixed '/'s - this has saved me multiple times as I every time I use one (at least in go) vscode tells me whether I need to add a / or not.

[silverwind]

Regarding slashes, we should just ensure the backend variables never contain a trailing slash (e.g. stripping it from config var), that way we can remove the joinPath function in JS too.