package configimport (	"fmt"	"os"	"time"	"github.com/BurntSushi/toml")type Config struct {	Site         `toml:"site"`	Server       `toml:"server"`	Session      `toml:"session"`	Registration `toml:"registration"`}type Site struct {	Name         string `toml:"name"`	Description  string `toml:"description"`	DefaultTheme string `toml:"default_theme"`}type Server struct {	Address string `toml:"address"`}type Session struct {	Secure   bool          `toml:"secure"`	Lifetime time.Duration `toml:"lifetime"`}type Registration struct {	Enabled            bool `toml:"enabled"`	RequireEmailVerify bool `toml:"require_email_verify"`	InviteOnly         bool `toml:"invite_only"`}var instance *Config// Get provides global access to application configfunc Get() *Config {	if instance == nil {		panic("Get called before initialization")	}	return instance}// MustLoad reads the config.toml file and globally initializes a Config.// Panics on os errors or unparsable configfunc MustLoad() {	// config.toml	data, err := os.ReadFile("config.toml")	if err != nil {		panic(fmt.Sprintf("unable to read config file: %v", err))	}	cfg := &Config{}	if _, err := toml.Decode(string(data), cfg); err != nil {		panic(fmt.Sprintf("error parsing config: %v", err))	}	instance = cfg}// MustEnv asserts that all required environment vars are set.// Panics on missing environment vars.func MustEnv(required ...string) {	var missing []string	for _, key := range required {		if _, ok := os.LookupEnv(key); !ok {			missing = append(missing, key)		}	}	if len(missing) > 0 {		panic(fmt.Sprintf("missing env values: %v", missing))	}}