The return of "Unexpected end of JSON input"

[kf6kjg]

This is a Bug Report

Description

The command npx sls deploy --conceal with the following environment variables set failed with the titular error message. After some hacking and searching I think I found the source of the problem, and I'd send in a PR however I'm not yet sure the correct multi-platform solution.

My config:

• Environment variables set via CLI:
  • NODE_ENV=staging
  • TS_NODE_PROJECT=webpack/tsconfig-for-webpack-config.json
• Relevant blocks from my serverless.yml:

custom:
  webpack:
    webpackConfig: webpack/webpack.ts
    includeModules: true

package:
  individually: true

plugins:
  - serverless-dotenv-plugin
  - serverless-offline
  - serverless-offline-scheduler
  - serverless-webpack

And several other things in my config that I'm nearly 100% sure are not relevant to the problem at hand.

Similar or dependent issue(s):

• Google and Firebase - Unexpected end of JSON input #309 - However yarn is not involved at all, just plain NPM.
• Do not swallow errors in case npm ls fails without an empty stdout and use spawn for child processes #373 - This PR changed the affected code to child_process.spawn, which was laudable, but it seems like Node may have changed at some point.

Additional Data

$ npm -v
6.14.4

• Serverless-Webpack Version you're using: "serverless-webpack": "^5.3.1"
• Webpack version you're using: "webpack": "^4.29.0"
• Serverless Framework Version you're using: "serverless": "^1.69.0"
• Operating System: Kubuntu 18.04.3 (equivalent to Ubuntu 18.04.3 LTS)
• Stack Trace (if available):

...
Serverless: Invoke webpack:package
  Syntax Error -------------------------------------------
 
  SyntaxError: Unexpected end of JSON input
      at JSON.parse (<anonymous>)
      at /home/ricky/data/dev_slidewave/serverless/node_modules/serverless-webpack/lib/packagers/npm.js:75:19
      at tryCatcher (/home/ricky/data/dev_slidewave/serverless/node_modules/bluebird/js/release/util.js:16:23)
      at Function.Promise.attempt.Promise.try (/home/ricky/data/dev_slidewave/serverless/node_modules/bluebird/js/release/method.js:39:29)
      at /home/ricky/data/dev_slidewave/serverless/node_modules/serverless-webpack/lib/packagers/npm.js:73:35
      at tryCatcher (/home/ricky/data/dev_slidewave/serverless/node_modules/bluebird/js/release/util.js:16:23)
      at Promise._settlePromiseFromHandler (/home/ricky/data/dev_slidewave/serverless/node_modules/bluebird/js/release/promise.js:547:31)
      at Promise._settlePromise (/home/ricky/data/dev_slidewave/serverless/node_modules/bluebird/js/release/promise.js:604:18)
      at Promise._settlePromise0 (/home/ricky/data/dev_slidewave/serverless/node_modules/bluebird/js/release/promise.js:649:10)
      at Promise._settlePromises (/home/ricky/data/dev_slidewave/serverless/node_modules/bluebird/js/release/promise.js:729:18)
      at _drainQueueStep (/home/ricky/data/dev_slidewave/serverless/node_modules/bluebird/js/release/async.js:93:12)
      at _drainQueue (/home/ricky/data/dev_slidewave/serverless/node_modules/bluebird/js/release/async.js:86:9)
      at Async._drainQueues (/home/ricky/data/dev_slidewave/serverless/node_modules/bluebird/js/release/async.js:102:5)
      at Immediate.Async.drainQueues [as _onImmediate] (/home/ricky/data/dev_slidewave/serverless/node_modules/bluebird/js/release/async.js:15:14)
      at processImmediate (internal/timers.js:456:21)
      at process.topLevelDomainCallback (domain.js:137:15)
 
  Your Environment Information ---------------------------
     Operating System:          linux
     Node Version:              13.14.0
     Framework Version:         1.69.0
     Plugin Version:            3.6.9
     SDK Version:               2.3.0
     Components Version:        2.30.4

As I said I did some digging and it seems that there's a buffering problem with the output of npm ls.
Manual execution of npm ls -prod -json -depth=1 > npmls.json results in npmls.txt.

So I utilized a concept from SO, though the unbuffer command isn't preinstalled on my system so I skipped the accepted answer's solution, and the stdbuf command didn't solve the problem. I modified npm.js::getProdDependencies as follows:

    const command = "script";
    const args = [
      '-q',
      '-c',
      `${/^win/.test(process.platform) ? 'npm.cmd' : 'npm'} ls -prod -json -depth=${depth || 1}`,
      '/dev/null'
    ];

Which, while having broad Linux support, won't work on BSD-based platforms or Windows. After making that change that error is resolved and I can proceed to the next problem to solve.

Thus this issue report: I found a solution, but it's not a good solution.

[kf6kjg]

Funny thing was that just yesterday I spent the whole day trying to figure out why a spawn call in my own code wasn't getting anything on stdin or sending anything on stdout, wound up anbanding spawn for an alternative I was able to get away with: the command I was calling was just another TypeScript module, so I refactored its core into a library module and called that via import instead of spawning a whole process. But I digress.

[ernesto-castelan-movile]

I was having this error using node 12.19.0 installed as a snap
I switched to this installation and the problem is resolved
https://github.com/nodesource/distributions/blob/master/README.md#deb