Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Shared/File.php
public static function assertFile($filename)
    {
        if (!is_file($filename)) {
            throw new InvalidArgumentException('File "' . $filename . '" does not exist.');
        }

        if (!is_readable($filename)) {
            throw new InvalidArgumentException('Could not open "' . $filename . '" for reading.');
        }
    }
public static function assertFile($filename)
    {
        if (!is_file($filename)) {
            throw new InvalidArgumentException('File "' . $filename . '" does not exist.');
        }

        if (!is_readable($filename)) {
            throw new InvalidArgumentException('Could not open "' . $filename . '" for reading.');
        }
    }
Assert that given path is an existing file and is readable, otherwise throw exception.

@param string $filename

@throws InvalidArgumentException