В оригинале
case GuardianSerializer.from_token(claims["sub"]) do
          {:ok, user} ->
            {:ok, assign(socket, :current_user, user)}
Пишу так
    case Guardian.Phoenix.Socket.authenticate(socket, ImconWeb.Guardian, token) do
      {:ok, user} ->
        {:ok, assign(socket, :current_user, user["sub"])}
В итоге ошибка
    ** (UndefinedFunctionError) function Phoenix.Socket.fetch/2 is undefined (Phoenix.Socket does not implement the Access behaviour)