test

a.php

<?php

echo "Hello World!";

bootstrap.sh

#!/bin/bash

curl --output composer.phar https://getcomposer.org/composer.phar
chmod +x composer.phar
./composer.phar install

composer.json

{
    "require-dev": {
        "vimeo/psalm": "^5.22"
    }
}

init.lua

vim.cmd [[set runtimepath=$VIMRUNTIME]]
vim.cmd [[set packpath=/tmp/nvim-repro-min/site]]
local package_root = "/tmp/nvim-repro-min/site/pack"
local install_path = package_root .. "/packer/start/packer.nvim"
local function load_plugins()
  require("packer").startup {
    {
      "wbthomason/packer.nvim",
      "neovim/nvim-lspconfig",
      "j-hui/fidget.nvim",
    },
    config = {
      package_root = package_root,
      compile_path = install_path .. "/plugin/packer_compiled.lua",
      display = { non_interactive = true },
    },
  }
end
if vim.fn.isdirectory(install_path) == 0 then
  print "Installing dependencies."
  vim.fn.system { "git", "clone", "--depth=1", "https://github.com/wbthomason/packer.nvim", install_path }
end
load_plugins()
require("packer").sync()
vim.cmd [[autocmd User PackerComplete ++once echo "Ready!" | lua setup()]]
vim.opt.termguicolors = true
vim.opt.cursorline = true

_G.setup = function()
  require("fidget").setup {
    progress = {
      lsp = {
        log_handler = true
      }
    },
    logger = {
      level = vim.log.levels.DEBUG,
      path = "/tmp/fidget.nvim.log",
    }
  }

  vim.lsp.set_log_level('debug')

  local nvim_lsp = require("lspconfig")
  nvim_lsp.tsserver.setup {}
  nvim_lsp.psalm.setup {
    cmd = { "./vendor/bin/psalm-language-server" },
    filetypes = { "php" },
  }

end

psalm.xml

<?xml version="1.0"?>
<psalm
  errorLevel="4"
  phpVersion="8.3"
  resolveFromConfigFile="true"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xmlns="https://getpsalm.org/schema/config"
  xsi:schemaLocation="https://getpsalm.org/schema/config tools/psalm/vendor/vimeo/psalm/config.xsd"
  allowStringToStandInForClass="true"
  findUnusedCode="false"
  findUnusedBaselineEntry="true"
>
  <projectFiles>
    <directory name="."/>
  </projectFiles>
</psalm>