message: Demote failure to apply a signature to warn
diff: @@ -814,7 +814,7 @@ impl BlockSynchronizer {
  if let Err(error) =
  builder.register_finality_signature(*finality_signature, maybe_peer)
  {
  - error!(%error, "BlockSynchronizer: failed to apply finality signature");
  + warn!(%error, "BlockSynchronizer: failed to apply finality signature");
  }
  }
  }
  