firebase-tools: Can't deploy any functions to Cloud Functions by CLI v8.1.0

[REQUIRED] Environment info

firebase-tools: 8.1.0 Platform: macOS

[REQUIRED] Test case

N/A

[REQUIRED] Steps to reproduce

firebase deploy --only functions

[REQUIRED] Expected behavior

deploy like previous versions

[REQUIRED] Actual behavior

firebase deploy --only functions --debug
[2020-04-17T02:12:04.556Z] > command requires scopes: ["email","openid","https://www.googleapis.com/auth/cloudplatformprojects.readonly","https://www.googleapis.com/auth/firebase","https://www.googleapis.com/auth/cloud-platform"]
[2020-04-17T02:12:04.557Z] > authorizing via signed-in user
[2020-04-17T02:12:04.557Z] [iam] checking project jirawatee-108d7 for permissions ["cloudfunctions.functions.create","cloudfunctions.functions.delete","cloudfunctions.functions.get","cloudfunctions.functions.list","cloudfunctions.functions.update","cloudfunctions.operations.get","firebase.projects.get"]
[2020-04-17T02:12:04.560Z] >>> HTTP REQUEST POST https://cloudresourcemanager.googleapis.com/v1/projects/jirawatee-108d7:testIamPermissions  
 {"permissions":["cloudfunctions.functions.create","cloudfunctions.functions.delete","cloudfunctions.functions.get","cloudfunctions.functions.list","cloudfunctions.functions.update","cloudfunctions.operations.get","firebase.projects.get"]}
[2020-04-17T02:12:05.949Z] <<< HTTP RESPONSE 200 {"content-type":"application/json; charset=UTF-8","vary":"X-Origin, Referer, Origin,Accept-Encoding","date":"Fri, 17 Apr 2020 02:12:07 GMT","server":"ESF","cache-control":"private","x-xss-protection":"0","x-frame-options":"SAMEORIGIN","x-content-type-options":"nosniff","server-timing":"gfet4t7; dur=1147","alt-svc":"quic=\":443\"; ma=2592000; v=\"46,43\",h3-Q050=\":443\"; ma=2592000,h3-Q049=\":443\"; ma=2592000,h3-Q048=\":443\"; ma=2592000,h3-Q046=\":443\"; ma=2592000,h3-Q043=\":443\"; ma=2592000,h3-T050=\":443\"; ma=2592000","accept-ranges":"none","transfer-encoding":"chunked"}
[2020-04-17T02:12:05.951Z] >>> HTTP REQUEST POST https://iam.googleapis.com/v1/projects/jirawatee-108d7/serviceAccounts/jirawatee-108d7@appspot.gserviceaccount.com:testIamPermissions  
 {"permissions":["iam.serviceAccounts.actAs"]}
[2020-04-17T02:12:07.788Z] <<< HTTP RESPONSE 200 {"content-type":"application/json; charset=UTF-8","vary":"X-Origin, Referer, Origin,Accept-Encoding","date":"Fri, 17 Apr 2020 02:12:09 GMT","server":"ESF","cache-control":"private","x-xss-protection":"0","x-frame-options":"SAMEORIGIN","x-content-type-options":"nosniff","alt-svc":"quic=\":443\"; ma=2592000; v=\"46,43\",h3-Q050=\":443\"; ma=2592000,h3-Q049=\":443\"; ma=2592000,h3-Q048=\":443\"; ma=2592000,h3-Q046=\":443\"; ma=2592000,h3-Q043=\":443\"; ma=2592000,h3-T050=\":443\"; ma=2592000","accept-ranges":"none","transfer-encoding":"chunked"}

=== Deploying to 'jirawatee-108d7'...

i  deploying functions
Running command: npm --prefix "$RESOURCE_DIR" run lint

> functions@ lint /Users/jirawatk/Documents/Git/Firebase/functions
> eslint .

✔  functions: Finished running predeploy script.
[2020-04-17T02:12:10.703Z] > [functions] package.json contents: {
  "name": "functions",
  "description": "Cloud Functions for Firebase",
  "scripts": {
    "lint": "eslint .",
    "serve": "firebase serve --only functions",
    "shell": "firebase experimental:functions:shell",
    "start": "npm run shell",
    "deploy": "firebase deploy --only functions",
    "logs": "firebase functions:log"
  },
  "dependencies": {
    "@google-cloud/vision": "^1.11.0",
    "child-process-promise": "^2.2.1",
    "firebase-admin": "^8.10.0",
    "firebase-functions": "^3.6.0",
    "googleapis": "^49.0.0",
    "mkdirp": "^1.0.4",
    "mkdirp-promise": "^5.0.1",
    "request": "^2.88.2",
    "request-promise": "^4.2.5"
  },
  "devDependencies": {
    "eslint": "^6.8.0",
    "eslint-plugin-promise": "^4.2.1"
  },
  "engines": {
    "node": "8"
  },
  "private": true
}
[2020-04-17T02:12:10.705Z] Error: ENOENT: no such file or directory, stat 'functions/package.json'
    at Object.statSync (fs.js:933:3)
    at Object.load (/usr/local/lib/node_modules/firebase-tools/node_modules/cjson/index.js:200:12)
    at getRuntimeChoice (/usr/local/lib/node_modules/firebase-tools/lib/parseRuntimeAndValidateSDK.js:55:26)
    at module.exports (/usr/local/lib/node_modules/firebase-tools/lib/deploy/functions/prepare.js:26:29)
    at _chain (/usr/local/lib/node_modules/firebase-tools/lib/deploy/index.js:22:40)
    at /usr/local/lib/node_modules/firebase-tools/lib/deploy/index.js:63:16
    at processTicksAndRejections (internal/process/task_queues.js:97:5)

Error: An unexpected error has occurred.