Require that input amount is provided for bitcoin-tx witness transactions

Co-authored-by: Sebastian Falbesoner <sebastian.falbesoner@gmail.com>

src/bitcoin-tx.cpp

@@ -630,7 +630,7 @@ static void MutateTxSign(CMutableTransaction& tx, const std::string& flagStr)
                 }
                 Coin newcoin;
                 newcoin.out.scriptPubKey = scriptPubKey;
-                newcoin.out.nValue = 0;
+                newcoin.out.nValue = MAX_MONEY;
                 if (prevOut.exists("amount")) {
                     newcoin.out.nValue = AmountFromValue(prevOut["amount"]);
                 }
@@ -669,6 +669,10 @@ static void MutateTxSign(CMutableTransaction& tx, const std::string& flagStr)
         if (!fHashSingle || (i < mergedTx.vout.size()))
             ProduceSignature(keystore, MutableTransactionSignatureCreator(&mergedTx, i, amount, nHashType), prevPubKey, sigdata);
 
+        if (amount == MAX_MONEY && !sigdata.scriptWitness.IsNull()) {
+            throw std::runtime_error(strprintf("Missing amount for CTxOut with scriptPubKey=%s", HexStr(prevPubKey)));
+        }
+
         UpdateInput(txin, sigdata);
     }