don't fail when body is empty

[ijsnow]

Description of the change

This change prevents an error being thrown by the rollbar sdk in a corner case where it thinks a response should be JSON but it is empty.

Both me and the original author of the fix couldn't cause a test to fail. In my opinion this shouldn't prevent this change from being fixed as it is minimal.

Type of change

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

Related issues

Shortcut stories and GitHub issues (delete irrelevant)

• Fix Error: SyntaxError: Unexpected end of JSON input when server response has no body but JSON content type #999

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 assigned
• Issue from task tracker has a link to this pull request
• Changes have been reviewed by at least one other engineer

[yjukaku]

Awesome, thanks!

[yjukaku]

Any ideas on when this change will be released to npm?