Approving an already approved request gives an error message

Issue Summary

In group approval configuration, when a request is already approved by one of the approvers of the group and when another user who is part of the same group tries to approve the request via email, they receive an error message "We couldn't record your selection".

Steps to Reproduce

1. Create a custom field of type Group Picker (multiple groups)
2. Create a group that has multiple approvers
3. Configure approval in your workflow
4. While creating issue, select the group approver created in Step 2
5. Say, Bill from the group has approved the request
6. If another user tries to approve the request via the "Approve" button in the email, they see the following error

Expected Results

This error message becomes misleading for the approvers. The error message can be changed to an informational message.

Actual Results

An error message appears "We couldn't record your selection"

Workaround

Currently there is no known workaround for this behaviour. A workaround will be added here when available