Jira should enable the ability to convert a bug to a story. Often when a defect is found, the effort to fix the issue is more complex and requires more effort. In this case, teams should be able to convert that defect to a story and retain all the artifacts in that defect similarly to how you allow bugs to be converted to sub-tasks. I would argue that the conversion to a story is more appropriate than converting to a sub-task, as that defects' complexity is more than just having a sub-task. I urge you to consider and implement the ability to allow defects to be converted to a story, and perhaps any issue type, if the complexity is not to high to do so.

Thank you