In

Zend_Log::_constructFilterFromConfig($config);

on line 159, the variable {{$filterName}} is undefined and an line 156 parentheses are missing.

if (!$filter instanceof Zend_Log_Filter_Interface) {
    /** @see Zend_Log_Exception */
    require_once 'Zend/Log/Exception.php';
    throw new Zend_Log_Exception("{$filterName} does not implement Zend_Log_Filter_Interface");
}

A fix could be (again, use of double quotation marks is discouraged, by the way):

if (!($filter instanceof Zend_Log_Filter_Interface)) {
    /** @see Zend_Log_Exception */
    require_once 'Zend/Log/Exception.php';
    $filterName = is_object($filter)
                ? get_class($filter)
                : 'The specified filter'
    ;
    throw new Zend_Log_Exception($filterName . 'does not implement Zend_Log_Filter_Interface.');
}