Neovim配置mason-lspconfig handlers时遇nil值错误求助

在配置nvim-lspconfig时，尝试自定义mason-lspconfig的handlers，触发了nil值错误，提示attempt to call field 'setup_handlers' (a nil value)。此前参考过nvim-luasnip的类似问题但未解决，怀疑是mason-lspconfig的setup_handlers返回nil导致。

配置代码 #

return {
  "neovim/nvim-lspconfig",
  event = { "BufReadPre", "BufNewFile" },
  dependencies = {
    "hrsh7th/cmp-nvim-lsp",
    { "antosha417/nvim-lsp-file-operations", config = true },
    { "folke/neodev.nvim", opts = {} },
  },
  config = function()
    -- import lspconfig plugin
    local lspconfig = require("lspconfig")

    -- import mason_lspconfig plugin
    local mason_lspconfig = require("mason-lspconfig")

    -- import cmp-nvim-lsp plugin
    local cmp_nvim_lsp = require("cmp_nvim_lsp")

    local keymap = vim.keymap -- for conciseness

    vim.api.nvim_create_autocmd("LspAttach", {
      group = vim.api.nvim_create_augroup("UserLspConfig", {}),
      callback = function(ev)
        -- Buffer local mappings.
        -- See `:help vim.lsp.*` for documentation on any of the below functions
        local opts = { buffer = ev.buf, silent = true }

        -- set keybinds
        opts.desc = "Show LSP references"
        keymap.set("n", "gR", "<cmd>Telescope lsp_references<CR>", opts) -- show definition, references

        opts.desc = "Go to declaration"
        keymap.set("n", "gD", vim.lsp.buf.declaration, opts) -- go to declaration

        opts.desc = "Show LSP definitions"
        keymap.set("n", "gd", "<cmd>Telescope lsp_definitions<CR>", opts) -- show lsp definitions

        opts.desc = "Show LSP implementations"
        keymap.set("n", "gi", "<cmd>Telescope lsp_implementations<CR>", opts) -- show lsp implementations

        opts.desc = "Show LSP type definitions"
        keymap.set("n", "gt", "<cmd>Telescope lsp_type_definitions<CR>", opts) -- show lsp type definitions

        opts.desc = "See available code actions"
        keymap.set({ "n", "v" }, "<leader>ca", vim.lsp.buf.code_action, opts) -- see available code actions, in visual mode will apply to selection

        opts.desc = "Smart rename"
        keymap.set("n", "<leader>rn", vim.lsp.buf.rename, opts) -- smart rename

        opts.desc = "Show buffer diagnostics"
        keymap.set("n", "<leader>D", "<cmd>Telescope diagnostics bufnr=0<CR>", opts) -- show  diagnostics for file

        opts.desc = "Show line diagnostics"
        keymap.set("n", "<leader>d", vim.diagnostic.open_float, opts) -- show diagnostics for line

        opts.desc = "Go to previous diagnostic"
        keymap.set("n", "[d", vim.diagnostic.goto_prev, opts) -- jump to previous diagnostic in buffer

        opts.desc = "Go to next diagnostic"
        keymap.set("n", "]d", vim.diagnostic.goto_next, opts) -- jump to next diagnostic in buffer

        opts.desc = "Show documentation for what is under cursor"
        keymap.set("n", "K", vim.lsp.buf.hover, opts) -- show documentation for what is under cursor

        opts.desc = "Restart LSP"
        keymap.set("n", "<leader>rs", ":LspRestart<CR>", opts) -- mapping to restart lsp if necessary
      end,
    })

    -- used to enable autocompletion (assign to every lsp server config)
    local capabilities = cmp_nvim_lsp.default_capabilities()

    -- Change the Diagnostic symbols in the sign column (gutter)
    local signs = { Error = " ", Warn = " ", Hint = "󰠠 ", Info = " " }
    for type, icon in pairs(signs) do
      local hl = "DiagnosticSign" .. type
      vim.fn.sign_define(hl, { text = icon, texthl = hl, numhl = "" })
    end

    mason_lspconfig.setup_handlers({
      -- default handler for installed servers
      function(server_name)
        lspconfig[server_name].setup({
          capabilities = capabilities,
        })
      ["emmet_ls"] = function()
        -- configure emmet language server
        lspconfig["emmet_ls"].setup({
          capabilities = capabilities,
          filetypes = { "html", "typescriptreact", "javascriptreact", "css", "sass", "scss", "less", "svelte" },
        })
      end,
      ["lua_ls"] = function()
        -- configure lua server (with special settings)
        lspconfig["lua_ls"].setup({
          capabilities = capabilities,
          settings = {
            Lua = {
              -- make the language server recognize "vim" global
              diagnostics = {
                globals = { "vim" },
              },
              completion = {
                callSnippet = "Replace",
              },
            },
          },
        })
      end,
      end,
    })
  end,
}

错误输出 #

Failed to run `config` for nvim-lspconfig

...ister/.config/nvim/lua/meister/plugins/lsp/lspconfig.lua:81: attempt to call field 'setup_handlers' (a nil value)

# stacktrace:
  - lua/meister/plugins/lsp/lspconfig.lua:81 _in_ **config**
  - vim/_editor.lua:0
  - /auto-session/lua/auto-session/init.lua:746 

解决方案 #

1. 补充缺失的依赖 #

当前lazy.nvim配置的nvim-lspconfig未声明mason-lspconfig为依赖，导致插件可能未正确安装或加载顺序错误，无法找到setup_handlers方法。

修改dependencies部分，添加mason-lspconfig：

dependencies = {
  "hrsh7th/cmp-nvim-lsp",
  { "antosha417/nvim-lsp-file-operations", config = true },
  { "folke/neodev.nvim", opts = {} },
  "williamboman/mason-lspconfig.nvim", -- 新增依赖
},

2. 修复setup_handlers的语法错误 #

原代码中默认handler的函数未正确闭合，且缺少逗号分隔，导致Lua解析错误，间接引发nil值问题。

修正后的setup_handlers代码：

mason_lspconfig.setup_handlers({
  -- default handler for installed servers
  function(server_name)
    lspconfig[server_name].setup({
      capabilities = capabilities,
    })
  end, -- 补充闭合默认handler的end
  ["emmet_ls"] = function()
    -- configure emmet language server
    lspconfig["emmet_ls"].setup({
      capabilities = capabilities,
      filetypes = { "html", "typescriptreact", "javascriptreact", "css", "sass", "scss", "less", "svelte" },
    })
  end,
  ["lua_ls"] = function()
    -- configure lua server (with special settings)
    lspconfig["lua_ls"].setup({
      capabilities = capabilities,
      settings = {
        Lua = {
          -- make the language server recognize "vim" global
          diagnostics = {
            globals = { "vim" },
          },
          completion = {
            callSnippet = "Replace",
          },
        },
      },
    })
  end,
})

内容的提问来源于stack exchange，提问作者AMAN KUMAR