Error cause is not displayed when PM2 is started in cluster mode

[OliverJAsh]

What's going wrong?

Error cause is not displayed when PM2 is started in cluster mode.

How could we reproduce this issue?

package.json:

{
  "dependencies": {
    "pm2": "^5.3.1"
  }
}

server.js:

throw new Error("foo", {
  cause: new Error("bar"),
});

$ yarn run pm2-runtime --instances 1 server.js
yarn run v1.22.22
warning package.json: No license field
$ /Users/oliver/Code/reduced-test-cases/pm2-error-cause/node_modules/.bin/pm2-runtime --instances 1 server.js
2024-04-30T19:35:48: PM2 log: Launching in no daemon mode
2024-04-30T19:35:48: PM2 log: App [server:0] starting in -cluster mode-
2024-04-30T19:35:48: PM2 log: App [server:0] online
Error: foo
    at Object.<anonymous> (/Users/oliver/Code/reduced-test-cases/pm2-error-cause/server.js:1:7)
    at Module._compile (node:internal/modules/cjs/loader:1369:14)
    at Module._extensions..js (node:internal/modules/cjs/loader:1427:10)
    at Module.load (node:internal/modules/cjs/loader:1206:32)
    at Module._load (node:internal/modules/cjs/loader:1022:12)
    at /Users/oliver/Code/reduced-test-cases/pm2-error-cause/node_modules/pm2/lib/ProcessContainer.js:304:25
    at wrapper (/Users/oliver/Code/reduced-test-cases/pm2-error-cause/node_modules/pm2/node_modules/async/internal/once.js:12:16)
    at next (/Users/oliver/Code/reduced-test-cases/pm2-error-cause/node_modules/pm2/node_modules/async/waterfall.js:96:20)
    at /Users/oliver/Code/reduced-test-cases/pm2-error-cause/node_modules/pm2/node_modules/async/internal/onlyOnce.js:12:16
    at /Users/oliver/Code/reduced-test-cases/pm2-error-cause/node_modules/pm2/lib/Utility.js:175:18
2024-04-30T19:35:48: PM2 log: App name:server id:0 disconnected
2024-04-30T19:35:48: PM2 log: App [server:0] exited with code [0] via signal [SIGINT]

If we remove --instances 1, PM2 will start in fork mode instead of cluster mode. There the issue does not reproduce:

$ yarn run pm2-runtime server.js
yarn run v1.22.22
warning package.json: No license field
$ /Users/oliver/Code/reduced-test-cases/pm2-error-cause/node_modules/.bin/pm2-runtime server.js
2024-04-30T19:36:22: PM2 log: Launching in no daemon mode
2024-04-30T19:36:22: PM2 log: App [server:0] starting in -fork mode-
2024-04-30T19:36:22: PM2 log: App [server:0] online
Error: foo
    at Object.<anonymous> (/Users/oliver/Code/reduced-test-cases/pm2-error-cause/server.js:1:7)
    at Module._compile (node:internal/modules/cjs/loader:1369:14)
    ... 7 lines matching cause stack trace ...
    at Module._load (node:internal/modules/cjs/loader:1022:12) {
  [cause]: Error: bar
      at Object.<anonymous> (/Users/oliver/Code/reduced-test-cases/pm2-error-cause/server.js:2:10)
      at Module._compile (node:internal/modules/cjs/loader:1369:14)
      at Module._extensions..js (node:internal/modules/cjs/loader:1427:10)
      at Module.load (node:internal/modules/cjs/loader:1206:32)
      at Module._load (node:internal/modules/cjs/loader:1022:12)
      at Object.<anonymous> (/Users/oliver/Code/reduced-test-cases/pm2-error-cause/node_modules/pm2/lib/ProcessContainerFork.js:33:23)
      at Module._compile (node:internal/modules/cjs/loader:1369:14)
      at Module._extensions..js (node:internal/modules/cjs/loader:1427:10)
      at Module.load (node:internal/modules/cjs/loader:1206:32)
      at Module._load (node:internal/modules/cjs/loader:1022:12)
}
2024-04-30T19:36:22: PM2 log: App [server:0] exited with code [1] via signal [SIGINT]