[R-package] prevent memory leak if pointer fails to allocate

[david-cortes]

As a follow up from #4597, this PR adds preventions in case an R external object pointer object fails to allocate. This should be an incredibly uncommon situation (failing to allocate 8 bytes), but it is in any case preventable.

[jameslamb]

/gha run r-valgrind

Workflow R valgrind tests has been triggered! 🚀
https://github.com/microsoft/LightGBM/actions/runs/1259876731

Status: failure ❌.

[jameslamb]

/gha run r-solaris

Workflow Solaris CRAN check has been triggered! 🚀
https://github.com/microsoft/LightGBM/actions/runs/1259876933

solaris-x86-patched: https://builder.r-hub.io/status/lightgbm_3.2.1.99.tar.gz-3d775c70bfe84fdca5ca15b055686492
solaris-x86-patched-ods: https://builder.r-hub.io/status/lightgbm_3.2.1.99.tar.gz-0a4b82574ffe4f5b9172f7025fe87935
Reports also have been sent to LightGBM public e-mail: https://yopmail.com?lightgbm_rhub_checks
Status: success ✔️.

[david-cortes]

The failing checks don't show any errors.

[jameslamb]

On https://github.com/microsoft/LightGBM/runs/3669905286?check_suite_focus=true, I see

Error: The operation was canceled.

And that the job runtime was 3 hours, which is the maximum we allow.

LightGBM/.github/workflows/r_valgrind.yml

Line 10 in c3b60c2

timeout-minutes: 180

This happens sometimes and is usually something transient related to the infrastructure behind GitHub Actions. I'll re-run the valgrind test.

[jameslamb]

/gha run r-valgrind

Workflow R valgrind tests has been triggered! 🚀
https://github.com/microsoft/LightGBM/actions/runs/1262796151

Status: success ✔️.

[jameslamb]

Looks like all the tests are passing, and I understand what's going on in this change. Thanks for the help!

[github-actions]

This pull request has been automatically locked since there has not been any recent activity since it was closed. To start a new related discussion, open a new issue at https://github.com/microsoft/LightGBM/issues including a reference to this.