How to handle user equal nil when it is not detected by ActiveRecord::RecordNotFound

I am learning programming only, Ruby on Rails in particular. The problem I face currently is that I doubt in which way to handle my issue is better regarding clean code and avoiding my code smells or probably something else.

So basically, I have users_controller where I check if my jwt is valid: I decode it, withdraw user_id and look for the user in DB by her id.

 def login
    user = decoded_user(permitted_params[:jwt])
    render json: user
  rescue ActiveRecord::RecordNotFound, JWT::DecodeError
    render status: 401, json: { error: 'invalid token' }.to_json
  end

As you can see, in case of invalid jwt or user is not found, it must render 401 error, but somehow when user is nil, rescue ActiveRecord::RecordNotFound does not detect it and render 200 status when I want it 401. When jwt is valid or empty, it all works fine.

I was thinking to wrap it into if else block in case of nil though to me it does not seem really skilled. Could you help me to refactor, please? Thanks!