Error using repl with python (windows)

[Perry3D]

Debug adapter definition and debug configuration

Created a python env with

python -m venv venv_depugpy
venv_depugpy/Scripts/activate.bat
pip install debugpy

Configuration in nvim:

dap.adapters.python = {
  type = 'executable';
  command = 'C:\\Users\\oli\\AppData\\Local\\nvim\\venv_debugpy\\Scripts\\python';
  args = { '-m', 'debugpy.adapter' };
  options = {
    detached = true;
  };
}

function getPythonEnv()
  local venv = os.getenv("VIRTUAL_ENV")
  if venv ~= nil then
    return string.format("%s\\bin\\python.exe", venv)
  end

  local cwd = vim.fn.getcwd()
  if vim.fn.executable(cwd .. '/venv/' .. getVenvSuffix()) == 1 then
    return cwd .. '/venv/' .. getVenvSuffix()
  elseif vim.fn.executable(cwd .. '/.venv/' .. getVenvSuffix()) == 1 then
    return cwd .. '/.venv/' .. getVenvSuffix()
  else
    if vim.loop.os_uname().sysname == 'Linux' then
      return '/usr/bin/python'
    elseif vim.loop.os_uname().sysname == 'Windows_NT' then
      return os.getenv('SCOOP') .. '/apps/python/current/python.exe'
    end
  end
end

dap.configurations.python = {
  {
    type = 'python';
    request = 'launch';
    name = "Launch file with venv";
    justMyCode = false;
    program = "${file}";
    pythonPath = getPythonEnv();
  },
}

Vim version is 0.7.2. But i also tried a nightly build

nvim-dap is from latest master branch:

commit 66d33b7585b42b7eac20559f1551524287ded353 (HEAD -> master, tag: 0.2.0, origin/master, origin/HEAD)
Author: Mathias Fussenegger <f.mathias@zignar.net>
Date:   Thu Aug 4 16:07:14 2022 +0200

    Ensure repl autocompletion doesn't trigger in other buffers

Debug adapter version

debugpy is 1.6.2, python is 3.10.4

Steps to Reproduce

• Open python file.
• Set breakpoint
• Run configuration
• Open repl buffer and insert print('hello')

Expected Result

hello should be printed in the buffer

Actual Result

Got an error message:

Error executing vim.schedule lua callback: vim/shared.lua:65: s: expected string, got nil
stack traceback:
	[C]: in function 'error'
	vim/shared.lua:662: in function 'validate'
	vim/shared.lua:65: in function 'gsplit'
	vim/shared.lua:130: in function 'split'
	...im-data\site\pack\packer\start\nvim-dap/lua/dap/repl.lua:156: in function 'callback'
	...data\site\pack\packer\start\nvim-dap/lua/dap/session.lua:834: in function <...data\site\pack\packer\start\nvim-dap/lua/dap/session.lua:830>

[mfussenegger]

This is a bug in debugpy, see microsoft/debugpy#985

[Perry3D]

I set log level to trace and executed print('hello') again:

[ DEBUG ] 2022-08-11T16:14:38Z+0200 ] ...data\site\pack\packer\start\nvim-dap/lua/dap/session.lua:1301 ]	"request"	{
  arguments = {
    context = "repl",
    expression = "print('hello')",
    frameId = 2
  },
  command = "evaluate",
  seq = 14,
  type = "request"
}
[ DEBUG ] 2022-08-11T16:14:38Z+0200 ] ...data\site\pack\packer\start\nvim-dap/lua/dap/session.lua:818 ]	{
  body = {
    category = "stdout",
    output = "hello"
  },
  event = "output",
  seq = 27,
  type = "event"
}
[ DEBUG ] 2022-08-11T16:14:38Z+0200 ] ...data\site\pack\packer\start\nvim-dap/lua/dap/session.lua:818 ]	{
  body = {
    category = "stdout",
    output = "\n"
  },
  event = "output",
  seq = 28,
  type = "event"
}
[ DEBUG ] 2022-08-11T16:14:38Z+0200 ] ...data\site\pack\packer\start\nvim-dap/lua/dap/session.lua:818 ]	{
  body = {
    category = "stdout",
    output = "hello",
    source = vim.empty_dict()
  },
  event = "output",
  seq = 29,
  type = "event"
}
[ DEBUG ] 2022-08-11T16:14:38Z+0200 ] ...data\site\pack\packer\start\nvim-dap/lua/dap/session.lua:818 ]	{
  body = {
    category = "stdout",
    output = "\n",
    source = vim.empty_dict()
  },
  event = "output",
  seq = 30,
  type = "event"
}
[ DEBUG ] 2022-08-11T16:14:38Z+0200 ] ...data\site\pack\packer\start\nvim-dap/lua/dap/session.lua:818 ]	{
  body = {
    presentationHint = vim.empty_dict(),
    variablesReference = 0
  },
  command = "evaluate",
  request_seq = 14,
  seq = 31,
  success = true,
  type = "response"
}

I am not sure if this is the same bug. If I understand correctly you executed a print(None) which should result in a string ('None').
I just do a print('hello').

[mfussenegger]

It's the same underlying problem. The result property is mandatory in the evaluate response and debugpy doesn't provide it. That's also visible in your log output:

{
  body = {
    presentationHint = vim.empty_dict(),
    variablesReference = 0
  },
  command = "evaluate",
  request_seq = 14,
  seq = 31,
  success = true,
  type = "response"
}

https://microsoft.github.io/debug-adapter-protocol/specification#Requests_Evaluate

[mfussenegger]

I'm closing this here given that I don't indent to add a client side workaround.

[Perry3D]

Just want to mention that the upstream fix from microsoft/debugpy#1063 is working. Installing the dev version with pip install git+https://github.com/microsoft/debugpy resolves the issue.