fix: add nullptr checks for new_pyobject_id [backport 2.9] #54598

Job	Run time
test_unit (dd-lib-python-init-test-django)	3m 25s
test_unit (dd-lib-python-init-test-django-gunicorn)	3m 24s
test_unit (dd-lib-python-init-test-django-gunicorn-alpine)	3m 31s
test_unit (dd-lib-python-init-test-django-uvicorn)	3m 24s
test_unit (dd-lib-python-init-test-django-no-perms)	3m 37s
test_unit (dd-lib-python-init-test-django-pre-installed)	3m 36s
test_unit (dd-lib-python-init-test-django-unsupported-python)	3m 46s
build-and-publish-test-image / wait_for_package	9s
build-and-publish-test-image / build_push / build_push	13m 37s
test-runner-test (dd-lib-python-init-test-django)	2m 56s
test-runner-test (dd-lib-python-init-test-django-gunicorn)	2m 48s
test-runner-test (dd-lib-python-init-test-django-uvicorn)	2m 56s
	47m 9s

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