fix: better message when mise has an error / warning

README.md

···
 Defaults
 ```lua
 {
-  -- Executable to run and the args to pass
+  -- Executable to run
   run = 'mise',
+  -- Args for the executable, set to "env --json --quiet" to ignore mise warnings
   args = 'env --json',
   -- Set to override the base PATH
   initial_path = vim.env.PATH,

lua/mise/init.lua

···
 	local full_command = options.run .. " " .. options.args
 	local env_sh = vim.fn.system(full_command)
 
+	-- mise will print out warnings: "mise WARN" without the "--quiet" flag
+	if string.find(env_sh, "^mise") then
+		local first_line = string.match(env_sh, "^[^\n]*")
+		log.error(first_line)
+		return nil
+	end
+
 	local ok, data = pcall(vim.json.decode, env_sh)
 	if not ok or data == nil then
 		log.error('Invalid json returned by "' .. full_command .. '"')
···
 		set_previous(data)
 	end
 
-
 	local group = vim.api.nvim_create_augroup("mise.nvim", { clear = true })
 	vim.api.nvim_create_autocmd("DirChanged", {
 		group = group,
···
 	})
 
 	vim.api.nvim_create_user_command("Mise", function()
-		log.info(vim.inspect(get_data()));
+		log.info(vim.inspect(get_data()))
 	end, {
 		desc = "Mise",
 	})