check for undefined TagSet

[TimCsaky]

Description

• handle TagSet when undefined in S3 GetObjectTaggingCommand() response. steps to reproduce: mount add an empty Dell s3 bucket to coms upload a new file using S3 Browser/cyberduck call coms sync for the bucket. console shows error, new object not synced

• other coms endpoints that use this command but because we add coms-id tag by default, issue did not present.

Types of changes

Bug fix (non-breaking change which fixes an issue)

Checklist

• [x] I have read the CONTRIBUTING doc
• [x] I have checked that unit tests pass locally with my changes
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I have added necessary documentation (if appropriate)

Further comments

[github-actions[bot]]

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[jujaga]

Superceded by #204