src/CarteBlanche/App/Kernel.php
public function addPath($name, $value, $must_exists = false, $must_be_writable = false)
    {
        $config = $this->getContainer()->get('config');
        if ($must_exists) {
            $realpath = $this->getAbsolutePath($value);
            if (!empty($realpath)) {
                $value = $realpath;
            } else {
                DirectoryHelper::ensureExists($value);
                if (!file_exists($value)) {
                    $this->addBootError(
                        sprintf('Directory "%s" defined as an application path doesn\'t exist and can\'t be created!', $value)
                    );
/*
                    throw new RuntimeException(
                        sprintf('Directory "%s" defined as an application path doesn\'t exist and can\'t be created!', $value)
                    );
*/
                }
            }
        }
        if ($must_be_writable && !is_writable($value)) {
           $this->addBootError(
                sprintf('Directory "%s" must be writable! (%s)', $value, $name)
            );
/*
            throw new RuntimeException(
                sprintf('Directory "%s" must be writable!', $value)
            );
*/
        }
        $config->getRegistry()
            ->loadStack('paths')
            ->setEntry($name, $value)
            ->saveStack('paths', true);
        return $this;
    }
public function addPath($name, $value, $must_exists = false, $must_be_writable = false)
    {
        $config = $this->getContainer()->get('config');
        if ($must_exists) {
            $realpath = $this->getAbsolutePath($value);
            if (!empty($realpath)) {
                $value = $realpath;
            } else {
                DirectoryHelper::ensureExists($value);
                if (!file_exists($value)) {
                    $this->addBootError(
                        sprintf('Directory "%s" defined as an application path doesn\'t exist and can\'t be created!', $value)
                    );
/*
                    throw new RuntimeException(
                        sprintf('Directory "%s" defined as an application path doesn\'t exist and can\'t be created!', $value)
                    );
*/
                }
            }
        }
        if ($must_be_writable && !is_writable($value)) {
           $this->addBootError(
                sprintf('Directory "%s" must be writable! (%s)', $value, $name)
            );
/*
            throw new RuntimeException(
                sprintf('Directory "%s" must be writable!', $value)
            );
*/
        }
        $config->getRegistry()
            ->loadStack('paths')
            ->setEntry($name, $value)
            ->saveStack('paths', true);
        return $this;
    }
References a path value

@param string $name              The path reference
@param string $value             The path value
@param bool $must_exists         Check if concerned path exists
@param bool $must_be_writable    Check if concerned path is writable
@return self

@throws RuntimeException if the path does not exists and `$must_exists` is true
@throws ErrorException if the concerned path is not writable while it was required