fix: add nullptr checks for new_pyobject_id [backport 2.10]

[github-actions]

Backport e46c53b from #10131 to 2.10.

Checklist

• PR author has checked that all the criteria below are met
• The PR description includes an overview of the change
• The PR description articulates the motivation for the change
• The change includes tests OR the PR description describes a testing strategy
• The PR description notes risks associated with the change, if any
• Newly-added code is easy to change
• The change follows the library release note guidelines
• The change includes or references documentation updates if necessary
• Backport labels are set (if applicable)

Reviewer Checklist

• Reviewer has checked that all the criteria below are met
• Title is accurate
• All changes are related to the pull request's stated goal
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
• Release note makes sense to a user of the library
• If necessary, author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: backport-10131-to-2.10
Commit report: 1a94c5b
Test service: dd-trace-py

✅ 0 Failed, 109818 Passed, 3953 Skipped, 7m 2.77s Total duration (35m 13.76s time saved)

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 10.17%. Comparing base (c4d6251) to head (f654a7b).
Report is 5 commits behind head on 2.10.

Additional details and impacted files

@@            Coverage Diff             @@
##             2.10   #10133      +/-   ##
==========================================
- Coverage   11.80%   10.17%   -1.64%     
==========================================
  Files        1309     1309              
  Lines      124854   125041     +187     
==========================================
- Hits        14743    12724    -2019     
- Misses     110111   112317    +2206     

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[pr-commenter]

Benchmarks

Benchmark execution time: 2024-08-08 14:35:03

Comparing candidate commit f654a7b in PR branch backport-10131-to-2.10 with baseline commit 93089e0 in branch 2.10.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 221 metrics, 9 unstable metrics.