Make sure at least one utxo is there for Tr input

We can only omit non_witness_utxo for Tr if it has witness_utxo.

Author: LLFourn

src/psbt/mod.rs

@@ -965,7 +965,7 @@ impl PsbtInputExt for psbt::Input {
                 }
                 None => {
                     match derived {
-                        Descriptor::Tr(_) => { /*Tr outputs can always omit non_witness_utxo*/ }
+                        Descriptor::Tr(_) if check_witness_utxo => { /*can be omited*/ }
                         _ => return Err(UpdateInputError::NonWitnessUtxoCheck),
                     }
                 }