From 121c1487a3694854d9024dd48b09009adaf6af06 Mon Sep 17 00:00:00 2001
From: Dmitrii Shmatko <zilm13@users.noreply.github.com>
Date: Mon, 9 Oct 2023 21:33:53 +0300
Subject: [PATCH] Early fail on 0 active validators when computing sync
 committees (#7585)

---
 .../versions/altair/helpers/BeaconStateAccessorsAltair.java     | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/versions/altair/helpers/BeaconStateAccessorsAltair.java b/ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/versions/altair/helpers/BeaconStateAccessorsAltair.java
index fecb5bbcd56..21333cf8115 100644
--- a/ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/versions/altair/helpers/BeaconStateAccessorsAltair.java
+++ b/ethereum/spec/src/main/java/tech/pegasys/teku/spec/logic/versions/altair/helpers/BeaconStateAccessorsAltair.java
@@ -101,6 +101,8 @@ public IntList getNextSyncCommitteeIndices(final BeaconState state) {
     final UInt64 epoch = getCurrentEpoch(state).plus(1);
     final IntList activeValidatorIndices = getActiveValidatorIndices(state, epoch);
     final int activeValidatorCount = activeValidatorIndices.size();
+    checkArgument(activeValidatorCount > 0, "Provided state has no active validators");
+
     final Bytes32 seed = getSeed(state, epoch, Domain.SYNC_COMMITTEE);
     int i = 0;
     final SszList<Validator> validators = state.getValidators();