Error debugging on fresh phoenix 1.8 project

[Style12341]

Environment

• Elixir version (elixir -v): 1.18.4
• Phoenix version (mix deps): 1.8.0
• Operating system: Linux 6.16.0-5-cachyos

Actual behavior

Starting the debugger with Elixir LS on a fresh phoenix app, when typing localhost:4000, the following appears in the debug console

warning: a Mix listener expected by Phoenix.CodeReloader is missing.

Please add the listener to your mix.exs configuration, like so:

    def project do
      [
        ...,
        listeners: [Phoenix.CodeReloader]
      ]
    end


  (debugger 6.0.2) dbg_debugged.erl:95: :dbg_debugged.reply/1
  (debugger 6.0.2) dbg_debugged.erl:89: :dbg_debugged.handle_command/1
  (debugger 6.0.2) dbg_debugged.erl:77: :dbg_debugged.msg_loop/2
  (mix 1.18.4) lib/mix/sync/lock.ex:112: Mix.Sync.Lock.with_lock/3
  (debugger 6.0.2) dbg_debugged.erl:95: :dbg_debugged.reply/1
  (debugger 6.0.2) dbg_debugged.erl:89: :dbg_debugged.handle_command/1
  (debugger 6.0.2) dbg_debugged.erl:77: :dbg_debugged.msg_loop/2
  (stdlib 7.0.2) gen_server.erl:2470: :gen_server.try_handle_call/4
  (stdlib 7.0.2) gen_server.erl:2499: :gen_server.handle_msg/3
  (stdlib 7.0.2) proc_lib.erl:333: :proc_lib.init_p_do_apply/3

Expected behavior

It should run the debugger without any errors

[josevalim]

cc @lukaszsamson

[markquezada]

@josevalim FYI, we are also seeing this error after upgrading to 1.8

Elixir version (elixir -v): 1.18.1
Phoenix version (mix deps): 1.8.0
Operating system: mac os sonoma

[lukaszsamson]

Are you running with reloader turned on? It has known incompatibility with OTP debugger