Assertion at slot 8192

[arnetheduck]

INF 2019-03-08 01:58:04-06:00 Storing state                              tid=11707 stateRoot=34568B2765DF7853F87D9DEF88F27A83DDD421FE8C2F44D6EA78044DC704871C stateSlot=8192 node=9
INF 2019-03-08 01:58:04-06:00 Updated head                               tid=11707 headBlockRoot=44E30AF2 stateRoot=34568B27 stateSlot=8192 node=9
DBG 2019-03-08 01:58:04-06:00 Advancing state past slot gap              tid=11707 stateSlot=8192 targetSlot=8193 node=9
INF 2019-03-08 01:58:04-06:00 Scheduling next slot start action block    tid=11707 fromNow=5 slot=8194 node=9
DBG 2019-03-08 01:58:04-06:00 No new head found                          tid=11707 blockRoot=44E30AF2 stateRoot=34568B27 stateSlot=8192 node=9
DBG 2019-03-08 01:58:04-06:00 Advancing state past slot gap              tid=11707 stateSlot=8192 targetSlot=8193 node=9
beacon_node.nim(667)     beacon_node
beacon_node.nim(621)     run
asyncloop.nim(756)       runForever
asyncloop.nim(238)       poll
beacon_node.nim(417)     :anonymous
asyncmacro2.nim(306)     makeAttestation
asyncmacro2.nim(36)      makeAttestation_continue
beacon_node.nim(270)     makeAttestationIter
beaconstate.nim(278)     get_block_root
system.nim(3790)         failedAssertImpl
system.nim(3783)         raiseAssert
system.nim(2830)         sysFatal
[[reraised from:
beacon_node.nim(667)     beacon_node
beacon_node.nim(621)     run
asyncloop.nim(756)       runForever
asyncloop.nim(238)       poll
asyncfutures2.nim(370)   cb
]]
Error: unhandled exception: /home/arnetheduck/status/nim-beacon-chain/beacon_chain/spec/beaconstate.nim(278, 12) `state.slot <= slot + 8192` 
Async traceback:
  beacon_node.nim(667) beacon_node
  beacon_node.nim(621) run
  asyncloop.nim(756)   runForever
  asyncloop.nim(238)   poll
  beacon_node.nim(417) :anonymous
  asyncmacro2.nim(306) makeAttestation
  asyncmacro2.nim(36)  makeAttestation_continue
  beacon_node.nim(270) makeAttestationIter
  beaconstate.nim(278) get_block_root
  system.nim(3790)     failedAssertImpl
  system.nim(3783)     raiseAssert
  system.nim(2830)     sysFatal

I suspect it's related to us not finalizing stuff, and at the same time reaching the limit of some state history field

31a478e

[arnetheduck]

ok confirmed - we use get_block_root(state, get_epoch_start_slot(state.justified_epoch)) to get the block root for the justified_block_root field, but that only works for the last 8192 slots - after 13h of missing finalization, there will no longer be coverage..

[arnetheduck]

ethereum/consensus-specs#742