[Bug?]: Mysterious `Internal Error` message with no clues

[jamie-pate]

Self-service

• I'd be willing to implement a fix

Describe the bug

yarn 4.9.3 install yields this mysterious error

Internal Error: EACCES: permission denied, mkdir '/nonexistent'
Error: EACCES: permission denied, mkdir '/nonexistent'

After disecting the unminified code for yarn for 3 hours... I found that HOME=/nonexistent on the gcp VM I was using...

It would have saved me a bunch of time if there had been a better error message: e.g. 'Error .... while creating $HOME/.yarn

Final trace (line numbers will match this unminified version: unminified-yarn.zip )

Trace: mkdirpromise /nonexistent/.yarn/berry/cache { recursive: true }
    at /opt/flb/.yarn/releases/yarn-4.9.3.cjs:1763:21
    at new Promise (<anonymous>)
    at Yn.mkdirPromise (/opt/flb/.yarn/releases/yarn-4.9.3.cjs:1762:24)
    at t.setup (/opt/flb/.yarn/releases/yarn-4.9.3.cjs:45249:25)
    at async t.find (/opt/flb/.yarn/releases/yarn-4.9.3.cjs:45192:20)
    at async IC.execute (/opt/flb/.yarn/releases/yarn-4.9.3.cjs:121968:17)
    at async IC.validateAndExecute (/opt/flb/.yarn/releases/yarn-4.9.3.cjs:12418:19)
    at async t.run (/opt/flb/.yarn/releases/yarn-4.9.3.cjs:13520:17)
    at async ePt (/opt/flb/.yarn/releases/yarn-4.9.3.cjs:139389:7)
    at async GT (/opt/flb/.yarn/releases/yarn-4.9.3.cjs:139410:29)

To reproduce

Create a user where HOME=/nonexistent and try to run yarn install

Environment

System:
    OS: Linux 6.12 Debian GNU/Linux 13 (trixie) 13 (trixie)
    CPU: (4) x64 Intel(R) Xeon(R) Platinum 8481C CPU @ 2.70GHz
  Binaries:
    Node: 22.21.1 - /tmp/xfs-5241aca8/node
    Yarn: 4.9.3 - /tmp/xfs-5241aca8/yarn
    npm: 10.9.4 - /usr/bin/npm

Additional context

No response

[jamie-pate]

See
#1780
#5034