aliases: remove hacky workaround for warnings on strings (#457057)

      arg: lib.warn msg (v arg)

    else if lib.isList v then

      map (lib.warn msg) v

    else if lib.isString v then

      # Unlike the other cases, this changes the type of the value and

      # is therefore a breaking change for some code, but it’s the best

      # we can do.

      { __toString = lib.warn msg (lib.const v); }

    else

      # Can’t do better than this, and a `throw` would be more

      # disruptive for users…