Fix workaround for optional config file with Viper

There was a false error reported when the configuration file was found

bot/bot.go

@@ -126,15 +126,15 @@ func setupConfig() {
 	viper.SetConfigType("toml")
 	viper.AddConfigPath(".")
 
-	err = viper.ReadInConfig()
-
 	viper.BindEnv("DEBUG")
 	viper.BindEnv("DISCORD_TOKEN")
 	viper.BindEnv("OPEN_WEATHER_MAP_TOKEN")
 
+	if err := viper.ReadInConfig(); err != nil {
 		if _, ok := err.(viper.ConfigFileNotFoundError); !ok {
 			log.Fatalf("fatal error config file: %v", err)
 		}
+	}
 
 	err = viper.Unmarshal(&C)
 	if err != nil {