To avoid returning something in the root url, you could use a middleware to return a 404 not found for such URL:
Module.AddMiddleware(TAnonymousMiddleware.Create(
procedure(Context: THttpServerContext; Next: THttpServerProc)
begin
if Length(Module.GetRelativeSegments(Context.Request.Uri)) = 0 then
Context.Response.StatusCode := 404
else
Next(Context);
end
)
);