From 9d0014366a094bf571f8664a3e1e5b0928649a05 Mon Sep 17 00:00:00 2001
From: Sasha Bogicevic <sasha.bogicevic@iohk.io>
Date: Thu, 12 Jan 2023 13:31:31 +0100
Subject: [PATCH] Use first output as the head one in v_commit

---
 hydra-plutus/src/Hydra/Contract/Commit.hs | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/hydra-plutus/src/Hydra/Contract/Commit.hs b/hydra-plutus/src/Hydra/Contract/Commit.hs
index 79984e997d0..19ab90e37fe 100644
--- a/hydra-plutus/src/Hydra/Contract/Commit.hs
+++ b/hydra-plutus/src/Hydra/Contract/Commit.hs
@@ -98,9 +98,13 @@ validator (_party, _headScriptHash, _commit, headId) r ctx =
     ViaAbort ->
       traceIfFalse "ST not burned" (mustBurnST (txInfoMint $ scriptContextTxInfo ctx) headId)
     ViaCollectCom ->
-      traceIfFalse "ST is missing in the output" (hasST headId outputs)
+      traceIfFalse "ST is missing in the output" (hasST headId headOutputValue)
  where
-  outputs = foldMap txOutValue $ txInfoOutputs $ scriptContextTxInfo ctx
+  headOutputValue =
+    case txInfoOutputs (scriptContextTxInfo ctx) of
+      [] -> mempty
+      (headOutput : _) ->
+        txOutValue headOutput
 
 compiledValidator :: CompiledCode ValidatorType
 compiledValidator =