yarn exit 1 results in status 'online'

Problem 1: the command below fails to start a successfull process (as expected), yet pm2 shows as if it is 'online'.
Problem 2: if the command succeeds and runs a nextjs server, after a linux kill command of the node process, pm2 does not restart the process (it does restart it when I kill the parent yarn process)
What works: pm2 stop ... stop the started process. Also pm2 restart ... works.

So the following command ...
pm2 start yarn --name frontend-dk --restart-delay 30000 -- prod -p 3002
... results in a build/startup error with exit code 1:

/root/.pm2/logs/frontend-dk-out.log last 15 lines:
1|frontend | yarn run v1.22.18
1|frontend | $ next build && next start -p 3002
1|frontend | info  - Loaded env from /srv/frontend-dk/.env
1|frontend | info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

/root/.pm2/logs/frontend-dk-error.log last 15 lines:
1|frontend | > Build error occurred
1|frontend | Error: Specified images.domains should be an Array of strings received invalid values ().
1|frontend | See more info here: https://nextjs.org/docs/messages/invalid-images-config
1|frontend |     at assignDefaults (/srv/frontend-dk/node_modules/next/dist/server/config.js:289:23)
...
1|frontend |     at async Object.build [as default] (/srv/frontend-dk/node_modules/next/dist/build/index.js:55:25)
1|frontend | error Command failed with exit code 1.

Why is pm2 showing status as online? No proces was even started successfully.

# pm2 ls
┌─────┬────────────────────────┬─────────────┬─────────┬─────────┬──────────┬────────┬──────┬───────────┬──────────┬──────────┬──────────┬──────────┐
│ id  │ name                   │ namespace   │ version │ mode    │ pid      │ uptime │ ↺    │ status    │ cpu      │ mem      │ user     │ watching │
├─────┼────────────────────────┼─────────────┼─────────┼─────────┼──────────┼────────┼──────┼───────────┼──────────┼──────────┼──────────┼──────────┤
│ 1   │ frontend-dk            │ default     │ 0.39.1  │ fork    │ 152238   │ 78m    │ 0    │ online    │ 0%       │ 79.1mb   │ root     │ disabled │
└─────┴────────────────────────┴─────────────┴─────────┴─────────┴──────────┴────────┴──────┴───────────┴──────────┴──────────┴──────────┴──────────┘

Reproduce the reported command pm2 start yarn --name frontend-dk --restart-delay 30000 -- prod -p 3002 and inspect PM2's process-status and child-process handling. Compare the failed Yarn startup with killing the Node.js child and the parent Yarn process; done means exit code 1 is not shown as online and terminating the server child triggers a restart.