chore: Fix slash veto demo flake

l1-contracts/src/core/slashing/TallySlashingProposer.sol

@@ -487,8 +487,9 @@ contract TallySlashingProposer is EIP712 {
   /**
    * @notice Load committees for all epochs to be potentially slashed in a round from the rollup instance
    * @dev This is an expensive call. It is not marked as view since `getEpochCommittee` may modify rollup state.
+   *      If `getEpochCommittee` throws (eg committee not yet formed), an empty committee is returned for that epoch.
    * @param _round The round number to load committees for
-   * @return committees Array of committees, one for each epoch in the round
+   * @return committees Array of committees, one for each epoch in the round (may contain empty arrays for early epochs)
    */
   function getSlashTargetCommittees(SlashRound _round) external returns (address[][] memory committees) {
     committees = new address[][](ROUND_SIZE_IN_EPOCHS);
@@ -497,7 +498,11 @@ contract TallySlashingProposer is EIP712 {
     unchecked {
       for (uint256 epochIndex; epochIndex < ROUND_SIZE_IN_EPOCHS; ++epochIndex) {
         Epoch epoch = getSlashTargetEpoch(_round, epochIndex);
-        committees[epochIndex] = rollup.getEpochCommittee(epoch);
+        try rollup.getEpochCommittee(epoch) returns (address[] memory committee) {
+          committees[epochIndex] = committee;
+        } catch {
+          committees[epochIndex] = new address[](0);
+        }
       }
     }
 

l1-contracts/test/slashing/TallySlashingProposer.t.sol

@@ -864,4 +864,29 @@ contract TallySlashingProposerTest is TestBase {
       }
     }
   }
+
+  function test_getSlashTargetCommitteesEarlyEpochs() public {
+    // Test that getSlashTargetCommittees handles epochs 0 and 1 without throwing
+    // when ValidatorSelection__InsufficientValidatorSetSize is thrown
+
+    // Use a very early slash round that would target epochs 0 and 1
+    // With SLASH_OFFSET_IN_ROUNDS = 2, round 2 targets epochs starting from (2-2)*ROUND_SIZE_IN_EPOCHS = 0
+    SlashRound earlyRound = SlashRound.wrap(SLASH_OFFSET_IN_ROUNDS);
+
+    // This should not revert and should return empty committees for early epochs
+    address[][] memory committees = slashingProposer.getSlashTargetCommittees(earlyRound);
+
+    // Verify we get the expected number of committees
+    assertEq(committees.length, ROUND_SIZE_IN_EPOCHS, "Should return correct number of committees");
+
+    // For very early rounds, we expect empty committees for epochs 0 and 1
+    // Since ROUND_SIZE_IN_EPOCHS = 2, both epochs should be empty
+    for (uint256 i = 0; i < ROUND_SIZE_IN_EPOCHS; i++) {
+      Epoch targetEpoch = slashingProposer.getSlashTargetEpoch(earlyRound, i);
+      if (Epoch.unwrap(targetEpoch) <= 1) {
+        assertEq(committees[i].length, 0, "Committee for early epochs should be empty");
+      }
+      // For epochs > 1, we might get actual committees, but that depends on the test setup
+    }
+  }
 }