Undefined variable: country_codes

Hi guys.

There is something wrong with get_countrycodes() function in tools.php file, because I get constantly this PHP error:

[25-Feb-2018 10:14:13 UTC] PHP Notice:  Undefined variable: country_codes in 
../wp-content/plugins/google-analytics-dashboard-for-wp/tools/tools.php on line 20

I figured that:

		public static function get_countrycodes() {
			include_once 'iso3166.php';
			return $country_codes;
		}

include_once doesn’t include (or doesn’t assing values to variable?) that file and that’s why $country_codes is not defined.

But, when I changed it to include (or require) it seems to be ok and no error are returned.

Cheers

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