How to use the proper-lockfile.unlock function in proper-lockfile

private async doWithPreferenceFile(withPreferenceFile: WithPreferenceFile): Promise {
        await lock(this.filePath, { retries: 5 });
        const prefs = await this.read();
        let result;
        try {
            result = await withPreferenceFile(prefs);
            if (result.save) {
                await fs.writeJson(this.filePath, prefs);
            }
        } catch (e) {
            logger.error(`Operation on preference file failed: ${e.message}`);
        }
        await unlock(this.filePath);
        return result.value as V;
    }

.catch(err => {
                locker.unlock(filepath, { realpath: false }).catch(unlockErr => {
                    logger.error(`Failed to unlock ${filepath}: ${unlockErr}`);
                });
                return Q.reject(err);
            });
    }

        await new Promise((resolve, reject) => lockfile.unlock(resolved, {
            realpath: false
        }, err => err ? reject(err) : resolve()));
    }