Fix potential use after free issues

[piste-jp]

The problem was found by code scan. Use delete safe iteration instead.

Summary of changes

This pull request includes following changes or fixes.

• Fix of issue Fix code scanning alert - Potential use after free #457

Description

The CodeQL on the GitHub found three potential use after free issues. All are same flavor, it
means, use a pointer after free. So change the logic from normal iteration to delete safe iteration.

This fix might be good to merge to the v2.4-stable branch also.

Fixes #457

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have confirmed my fix is effective or that my feature works