将woocommerce货币功能添加到functions.php会导致白屏死机

Add this the following function to my functions.php file cause the white screen of death. The website appears fine when i remove this function:

add_filter( 'woocommerce_currencies', 'add_my_currency' );

function add_my_currency( $currencies ) {
  $currencies['KES'] = __( 'Kenyan Shillings', 'woocommerce' );
  return $currencies;
}

add_filter('woocommerce_currency_symbol', 'add_my_currency_symbol', 10, 2);

function add_my_currency_symbol( $currency_symbol, $currency ) {
   switch( $currency ) {
      case 'KES': $currency_symbol = 'KSH'; break;
   }
   return $currency_symbol;
}    

I found the culprit was a plugin. Deactivating it, solved the problem.