hotfix: Ensure that withdraw and unbond output values are below dust …

…and positive

package.json

@@ -1,6 +1,6 @@
 {
   "name": "btc-staking-ts",
-  "version": "0.2.6",
+  "version": "0.2.7",
   "description": "Library exposing methods for the creation and consumption of Bitcoin transactions pertaining to Babylon's Bitcoin Staking protocol. Experimental version, should not be used for production purposes or with real funds.",
   "module": "dist/index.js",
   "main": "dist/index.cjs",

src/index.ts

@@ -331,20 +331,19 @@ function withdrawalTransaction(
     sequence: timelock,
   });
 
-  const outputValue = tx.outs[outputIndex].value;
-  if (outputValue < BTC_DUST_SAT) {
-    throw new Error("Output value is less than dust limit");
-  }
   const estimatedFee = getWithdrawTxFee(feeRate);
-  const value = tx.outs[outputIndex].value - estimatedFee;
-  if (!value) {
+  const outputValue = tx.outs[outputIndex].value - estimatedFee;
+  if (outputValue < 0) {
     throw new Error(
       "Not enough funds to cover the fee for withdrawal transaction",
     );
   }
+  if (outputValue < BTC_DUST_SAT) {
+    throw new Error("Output value is less than dust limit");
+  }
   psbt.addOutput({
     address: withdrawalAddress,
-    value,
+    value: outputValue,
   });
 
   return {
@@ -680,16 +679,19 @@ export function unbondingTransaction(
     scriptTree: outputScriptTree,
     network,
   });
-  const value = stakingTx.outs[outputIndex].value - transactionFee;
-  if (!value) {
+  const outputValue = stakingTx.outs[outputIndex].value - transactionFee;
+  if (outputValue < 0) {
     throw new Error(
       "Not enough funds to cover the fee for unbonding transaction",
     );
   }
+  if (outputValue < BTC_DUST_SAT) {
+    throw new Error("Output value is less than dust limit");
+  }
   // Add the unbonding output
   psbt.addOutput({
     address: unbondingOutput.address!,
-    value: stakingTx.outs[outputIndex].value - transactionFee,
+    value: outputValue,
   });
 
   return {