Deleting VM disk snapshot may result in broken CLI output

[paczerny]

To Reproduce
Create a VM with disk

$ onevm disk-snapshot-create <vm-id> <disk-id> snapshot1

$ onevm disk-snapshot-delete <vm-id> <disk-id> snapshot1

# Now the VM doesn't have any disk snapshots

$ onevm show <vm-id>
VIRTUAL MACHINE 1 INFORMATION                                                   
.
.
.
VM DISK SNAPSHOTS                                                               
undefined method `merge' for nil:NilClass

Details

• Affected Component: CLI
• Version: 6.8+

Progress Status

• Code committed
• Testing - QA
• Documentation (Release notes - resolved issues, compatibility, known issues)