f Check for witness output differently

We can't check that `non_witness_utxo` is never `Some(..)` since the
`TxBuilder` might populate both `witness_utxo` and `non_witness_utxo` to
mitigate the "SegWit bug".

Author: tnull

src/access.rs

@@ -245,11 +245,12 @@ where
 		tx_builder.add_recipient(output_script.clone(), value_sats).fee_rate(fee_rate).enable_rbf();
 
 		let (mut psbt, _) = tx_builder.finish()?;
+		log_trace!(self.logger, "Created funding PSBT: {:?}", psbt);
 
 		// We double-check that no inputs try to spend non-witness outputs. As we use a SegWit
-		// wallet descriptor this technically can't ever happen, but better safe than sorry.
+		// wallet descriptor this technically shouldn't ever happen, but better safe than sorry.
 		for input in &psbt.inputs {
-			if input.non_witness_utxo.is_some() {
+			if input.witness_utxo.is_none() {
 				return Err(Error::FundingTxNonWitnessOuputSpend);
 			}
 		}