Live-reload doesn't send SSE event with `write: false` when `outdir` is `/`

[somebody1234]

This might be because currently change events must specify the list of changed files - but "reload on any change" would (should) be possible even when write: false

[somebody1234]

After further testing it only happens when outdir is /. This might be intentional but it'd be nice to output a warning when using watch + serve + outdir: "/"