fix lsp setup error

lua/rua/plugins/lang/rust.lua

@@ -1,4 +1,4 @@
-local rust_settings = require("rua.config.rust-analyzer")
+local rok, rust_settings = pcall(require, "rua.config.rust-analyzer")
 
 return {
   {

lua/rua/plugins/lsp/lspconfig.lua

@@ -5,7 +5,9 @@ return {
       { "hrsh7th/cmp-nvim-lsp" },
       { "antosha417/nvim-lsp-file-operations", config = true },
       { "folke/neodev.nvim", opts = {} },
+      "williamboman/mason-lspconfig.nvim",
     },
+    event = "VeryLazy",
     opts = { document_highlight = { enabled = false } },
     config = function()
       local lspconfig = require("lspconfig")