I have re-read documentation and it seems error_tracker provides an option as to change live_session’s name which fixes the error.

Example of working code:

if Application.compile_env(:justrunit, :dev_routes) do
    import Phoenix.LiveDashboard.Router

    scope "/dev" do
    pipe_through :browser

    live_dashboard "/dashboard", metrics: JustrunitWeb.Telemetry
    forward "/mailbox", Plug.Swoosh.MailboxPreview
    error_tracker_dashboard("/errors", as: :error_tracker_dashboard_dev)
  end
end

scope "/", JustrunitWeb.Modules do
  pipe_through [:browser, :require_authenticated_user, :error_tracker_access_check]

  error_tracker_dashboard("/errors", as: :error_tracker_dashboard_admin)
end