[BUG] deta is not optional

[guotie]

问题描述 | Describe the bug

问题网站 | Website URL

https://defihub-api.vercel.app/

部署方式 | Deploy Type

vercel

• [x] LeanCloud(https://leancloud.app)

logs:

[GET] /
18:57:54:00
2021-10-17T10:57:57.837Z    undefined   ERROR   Cannot find module 'deta'
Require stack:
- /var/task/node_modules/@waline/vercel/src/service/storage/deta.js
- /var/task/node_modules/think-loader/loader/util.js
- /var/task/node_modules/think-loader/loader/config.js
- /var/task/node_modules/think-loader/index.js
- /var/task/node_modules/thinkjs/lib/loader.js
- /var/task/node_modules/thinkjs/lib/application.js
- /var/task/node_modules/@waline/vercel/index.js
- /var/task/index.js
2021-10-17T10:57:57.837Z    undefined   ERROR   Did you forget to add it to "dependencies" in `package.json`?
RequestId: 860783de-de1c-4298-815f-6f27fff02993 Error: Runtime exited with error: exit status 1
Runtime.ExitError

[Mister-Hope]

Seems to be a bug, cc @lizheming