Cannot find module '@azure/identity' on Vercel

I deployed express app to Vercel. I'm using mssql library to connect MSSQL. I tested my express app on my local and it works fine. But after deploy to vercel, I see this error.

Cannot find module '@azure/identity'

Require stack:

/var/task/server/node_modules/tedious/lib/connection.js
/var/task/server/node_modules/tedious/lib/tedious.js
/var/task/server/node_modules/mssql/lib/tedious/connection-pool.js
/var/task/server/node_modules/mssql/lib/tedious/index.js
/var/task/server/node_modules/mssql/index.js
/var/task/server/src/app.js
/var/task/server/index.js
/var/task/___now_launcher.js
/var/runtime/index.mjs Did you forget to add it to "dependencies" in package.json? INIT_REPORT Init Duration: 223.72 ms Phase: init Status: error Error Type: Runtime.ExitError Cannot find module '@azure/identity' Require stack:
/var/task/server/node_modules/tedious/lib/connection.js
/var/task/server/node_modules/tedious/lib/tedious.js
/var/task/server/node_modules/mssql/lib/tedious/connection-pool.js
/var/task/server/node_modules/mssql/lib/tedious/index.js
/var/task/server/node_modules/mssql/index.js
/var/task/server/src/app.js
/var/task/server/index.js
/var/task/___now_launcher.js
/var/runtime/index.mjs Did you forget to add it to "dependencies" in package.json? INIT_REPORT Init Duration: 414.58 ms Phase: invoke Status: error Error Type: Runtime.ExitError Error: Runtime exited with error: exit status 1

Could you help me?

Also, I installed @azure/identity as well, but it didn't effect. (On local, it working without install @azure/identity separately)

Solution

I solved this problem by updating vercel.json

{
  "version": 2,
  "builds": [
    {
      "src": "index.js",
      "use": "@vercel/node"
    }
  ],
  "routes": [
    {
      "src": "/(.*)",
      "dest": "/"
    }
  ]
}