Question about setup_handlers

[u0398]

I'm trying to use setup_handlers, but without success, and I feel like I'm missing something fundamental. Here is the relevant code:

  local mason = require('mason')
  local mason_lspconfig = require('mason-lspconfig')
  local lspconfig = require('lspconfig')

  local lsp_capabilities = require('cmp_nvim_lsp').default_capabilities()

  local default_setup = function(server)
    require('lspconfig')[server].setup {
      capabilities = lsp_capabilities,
    }
  end

  mason.setup {
    ui = {
      icons = {
        package_installed = "✓",
        package_pending = "➜",
        package_uninstalled = "✗"
      }
    }
  }

  mason_lspconfig.setup {
    ensure_installed = { 'lua_ls' },
    automatic_installation = true,
  }

  mason_lspconfig.setup_handlers {
    default_setup,
    ['lua_ls'] = function()
      lspconfig.lua_ls.setup {
        capabilities = lsp_capabilities,
        settings = {
          Lua = {
            runtime = {
              version = 'LuaJIT'
            },
            diagnostics = {
              globals = {'vim'},
            },
            workspace = {
              library = {
                vim.env.VIMRUNTIME,
              }
            }
          }
        }
      }
    end,
  }

The result I expect is for lua_ls to be setup, but it does not. What am I missing?

[u0398]

Posted to the wrong project. Sorry.