Since the matching route is ::/0, it does make sense to me to print this error message. The /128 route doesn’t exist.
However, I’m getting an error about ::/0 guinch# route -n get 2a00:5884:102:1::/64 route to: 2a00:5884:102:1:: destination: 2a00:5884:102:1:: mask: ffff:ffff:ffff:ffff:: interface: vio0 if address: 2a00:5884:102:1::9 priority: 4 (connected) flags: <UP,DONE,CLONING,CONNECTED> use mtu expire 0 0 0 guinch# route -n get ::/0 get net ::/0: not in table guinch# route -n get 2a00:5884::1 route to: 2a00:5884::1 destination: :: mask: :: gateway: fe80::209%vio0 interface: vio0 if address: fe80::5054:ff:fed4:f3fa%vio0 priority: 8 (static) flags: <UP,GATEWAY,DONE,STATIC> use mtu expire 218366 0 0 -- Alarig