find rust-analyzer automatically and display error when not found

lua/plugins/lsp.lua

@@ -171,8 +171,15 @@ return {
 		lazy = false,
 		ft = { "rust" },
 		config = function()
+			local rust_analyzer_path = vim.fn.trim(vim.fn.system("rustup which rust-analyzer"))
+			if rust_analyzer_path == "" then
+				vim.notify("rust-analyzer not found! Install it with: rustup component add rust-analyzer",
+					vim.log.levels.ERROR)
+				return
+			end
 			vim.g.rustaceanvim = {
 				server = {
+					cmd = { rust_analyzer_path },
 					on_attach = lsp_attach,
 					settings = {
 						-- rust-analyzer language server configuration