Merge pull request #6571 from RosettaCommons/roccomoretti/fix_copy_to_clipboard
[Foldit] Fix copy-to-clipboard error.
The reported copy-shared-solution-to-clipboard crash wasn't actually fixed by my previous fixes (PR #6559).
Instead, it looks like the issue is that the publish_solution API endpoint doesn't send back a JSON 'object', but instead sends an empty string. Be robust to this condition (where the API doesn't actually send anything back).
RELEASE NOTES: Fix issue with copy-to-clipboard in shared solutions panel.