GH-539-backport-1.x: Fix isset check

[bxsx]

Description of the change

Backport of the #539 to the 1.x version.

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Related issues

#539

Checklists

Development

• Lint rules pass locally
• The code changed/added as part of this pull request has been covered with tests
• All tests related to the changed code pass in development

Code review

• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• "Ready for review" label attached to the PR and reviewers mentioned in a comment
• Changes have been reviewed by at least one other engineer
• Issue from task tracker has a link to this pull request

[bishopb]

Let's make sure the implementation in main has full test coverage and is non breaking, before backporting.

[bxsx]

Since #546 is a successor to the backported #539, it seems this PR is no longer valid.

@bishopb If the new fix provided in #546 can be backported, please open a new PR for the backport.
Thanks!