Discard decrements that attempts to take more value than it is in the…

… head

We changed the decommitSnapshot that interprets the model into the real world to
expose the TxBodyOutputNegative Bug.
Because its an invalid action we dont want to deal with it, so we decided to discard it.

hydra-node/test/Hydra/Chain/Direct/TxTraceSpec.hs

@@ -314,8 +314,9 @@ instance StateModel Model where
   -- it tried to perform).
   validFailingAction :: Model -> Action Model a -> Bool
   validFailingAction Model{headState, latestSnapshot, alreadyContested, utxoInHead} = \case
-    -- Decrement{} ->
-    --   headState == Open
+    Decrement{snapshot} ->
+      headState == Open
+        && decommitUTxO snapshot `Set.isSubsetOf` utxoInHead
     -- Close{snapshot} ->
     --   headState == Open
     --     && snapshotNumber snapshot < latestSnapshot
@@ -508,7 +509,7 @@ decommitSnapshot :: ModelSnapshot -> (Snapshot Tx, MultiSignature (Snapshot Tx))
 decommitSnapshot ms =
   (snapshot, signatures)
  where
-  (utxo, toDecommit) = generateUTxOFromModelSnapshot ms{snapshotUTxO = mempty}
+  (utxo, toDecommit) = generateUTxOFromModelSnapshot ms
   snapshot =
     Snapshot
       { headId = mkHeadId Fixture.testPolicyId