This problem doesn't need a scheduled function to be defined.
Comment out these lines in functions/index.js:
//export const abc = !EMULATION && await import("./abc.js").then( mod => mod.abc() );
//export { abc } from './abc.js'
Follow steps in main README, to authenticate (and try deploying).
$ ./deploy.sh
The script will succeed.
...
Error: An unexpected error has occurred.
The deployment succeeds, but exiting the process fails.
More details are in firebase-debug.log:
$ tail -n 40 firebase-debug.log
...
[info] i functions: cleaning up build files...
[info]
[info] ✔ Deploy complete!
[info]
[info] Project Console: https://console.firebase.google.com/project/abc-3011/overview
[debug] [2022-10-30T16:32:40.762Z] Error: EBUSY: resource busy or locked, unlink '/work/firebase-debug.log'
at Object.unlinkSync (node:fs:1767:3)
at process.<anonymous> (/usr/local/share/.config/yarn/global/node_modules/firebase-tools/lib/bin/firebase.js:84:12)
at process.emit (node:events:525:35)
at process.exit (node:internal/process/per_thread:190:15)
at /usr/local/share/.config/yarn/global/node_modules/firebase-tools/lib/command.js:105:25
at runMicrotasks (<anonymous>)
at processTicksAndRejections (node:internal/process/task_queues:96:5)
[error]
[error] Error: An unexpected error has occurred.
It should not be a problem for firebase-tools, to be run under Docker (Alpine Linux image) and the log file having been mapped to host.
Work-around:
If one enables/disables the firebase-debug.log mapping in docker-compose.yml on a case-by-case basis, one can debug problems (line enabled) or deploy (line disabled).
This is, however, very clumsy in practise.
It may be rare for people to deploy from a sandbox, but it's not an unreasonable use case.
In this case, it's about onboarding new users to a repo, so they can be up and running as early as possible - doing first deployments without needing to set up CI/CD for it.