tersec

``` /github-runner/github-runner-node-01/workspace/nimbus-eth2/nimbus-eth2/beacon_chain/spec/datatypes/focil.nim(50, 59) Error: undeclared field: 'seconds' for type system.uint64 [type declared in /github-runner/github-runner-node-01/workspace/nimbus-eth2/nimbus-eth2/vendor/nimbus-build-system/vendor/Nim/lib/system/basic_types.nim(12, 3)] make: *** [Makefile:441: nimbus_beacon_node] Error 1 ```

https://github.com/status-im/nimbus-eth2/actions/runs/16248920772/job/45876335181?pr=7290 (the `linux-amd64` target, though it's representative here): ``` 2025-07-13T12:34:24.5405193Z /github-runner/github-runner-node-01/workspace/nimbus-eth2/nimbus-eth2/vendor/nim-ssz-serialization/ssz_serialization/digest.nim(35, 9) Hint: BLST SHA256 backend enabled [User] 2025-07-13T12:34:24.5412603Z /github-runner/github-runner-node-01/workspace/nimbus-eth2/nimbus-eth2/vendor/nim-ssz-serialization/ssz_serialization/digest.nim(49, 9) Hint: Hashtree SHA256 backend enabled [User] 2025-07-13T12:34:27.1689107Z /github-runner/github-runner-node-01/workspace/nimbus-eth2/nimbus-eth2/beacon_chain/spec/datatypes/focil.nim(19, 8)...

> an alternative would be to remove `Union` entirely 🙈 well - https://github.com/ethereum/consensus-specs/pull/3906

Why have the field at all then? The block can't be canonical if `is_data_available(data.beacon_block_root)` is `False`.