## Issue Addressed
Closes#4751
## Proposed Changes
Prevent `state_root_at_slot` and `block_root_at_slot` from erroring out due to a call to `self.slot()?` that fails before genesis. This fixes pre-genesis queries for:
- block at slot 0
- block by genesis block root
- state at slot 0
- state by genesis state root
- state at `finalized` tag
- state at `justified` tag