Fix remote upfront script codec (#1991)

The script wasn't length-delimited.
Fortunately this feature was disabled by default.
Since no-one reported the issue, we can probably just do this simple fix.

eclair-core/src/main/scala/fr/acinq/eclair/wire/internal/channel/version3/ChannelCodecs3.scala

@@ -94,7 +94,7 @@ private[channel] object ChannelCodecs3 {
         ("delayedPaymentBasepoint" | publicKey) ::
         ("htlcBasepoint" | publicKey) ::
         ("features" | combinedFeaturesCodec) ::
-        ("shutdownScript" | optional(bool8, bytes))).as[RemoteParams]
+        ("shutdownScript" | optional(bool8, lengthDelimited(bytes)))).as[RemoteParams]
 
     def setCodec[T](codec: Codec[T]): Codec[Set[T]] = listOfN(uint16, codec).xmap(_.toSet, _.toList)
 

eclair-core/src/test/scala/fr/acinq/eclair/wire/internal/channel/version3/ChannelCodecs3Spec.scala

@@ -94,6 +94,12 @@ class ChannelCodecs3Spec extends AnyFunSuite {
     assert(remoteParamsCodec.decodeValue(remoteParamsCodec.encode(remoteParams).require).require === remoteParams)
     val remoteParams1 = remoteParams.copy(shutdownScript = Some(ByteVector.fromValidHex("deadbeef")))
     assert(remoteParamsCodec.decodeValue(remoteParamsCodec.encode(remoteParams1).require).require === remoteParams1)
+
+    val dataWithoutRemoteShutdownScript = normal.copy(commitments = normal.commitments.copy(remoteParams = remoteParams))
+    assert(DATA_NORMAL_Codec.decode(DATA_NORMAL_Codec.encode(dataWithoutRemoteShutdownScript).require).require.value === dataWithoutRemoteShutdownScript)
+
+    val dataWithRemoteShutdownScript = normal.copy(commitments = normal.commitments.copy(remoteParams = remoteParams1))
+    assert(DATA_NORMAL_Codec.decode(DATA_NORMAL_Codec.encode(dataWithRemoteShutdownScript).require).require.value === dataWithRemoteShutdownScript)
   }
 
   test("backward compatibility DATA_NORMAL_COMPAT_02_Codec") {