firefly-iii/app/Helpers/Csv/Converter/Amount.php

<?php

namespace FireflyIII\Helpers\Csv\Converter;

use FireflyIII\Models\Account;

/**
 * Class Amount
 *
 * @package FireflyIII\Helpers\Csv\Converter
 */
class Amount extends BasicConverter implements ConverterInterface
{

    /**
     * @return Account|null
     */
    public function convert()
    {
        if (is_numeric($this->value)) {
            return $this->value;
        }

        return 0;
    }
}