fix: getSignInput bug for zero maxPriorityFeePerGas

Explicit zero value should not fallback to maxFeePerGas

Author: everdimension

src/signer.ts

@@ -110,7 +110,7 @@ export class EIP712Signer {
   static getSignInput(transaction: TransactionRequest) {
     const maxFeePerGas = transaction.maxFeePerGas || transaction.gasPrice || 0n;
     const maxPriorityFeePerGas =
-      transaction.maxPriorityFeePerGas || maxFeePerGas;
+      transaction.maxPriorityFeePerGas ?? maxFeePerGas;
     const gasPerPubdataByteLimit =
       transaction.customData?.gasPerPubdata || DEFAULT_GAS_PER_PUBDATA_LIMIT;
     return {

tests/unit/signer.test.ts

@@ -63,7 +63,35 @@ describe('EIP712Signer', () => {
       });
       expect(result).to.be.deep.equal(tx);
     });
+
+    it('should correcly handle zero values', async () => {
+      const tx = {
+        txType: utils.EIP712_TX_TYPE,
+        from: ADDRESS1,
+        to: ADDRESS2,
+        gasLimit: 0n,
+        gasPerPubdataByteLimit: utils.DEFAULT_GAS_PER_PUBDATA_LIMIT,
+        maxFeePerGas: 250_000_000n,
+        maxPriorityFeePerGas: 0n,
+        paymaster: ethers.ZeroAddress,
+        nonce: 0,
+        value: 0n,
+        data: '0x',
+        factoryDeps: [],
+        paymasterInput: '0x',
+      };
+
+      const result = EIP712Signer.getSignInput({
+        type: utils.EIP712_TX_TYPE,
+        to: ADDRESS2,
+        from: ADDRESS1,
+        maxFeePerGas: 250_000_000n,
+        maxPriorityFeePerGas: 0n,
+      });
+      expect(result).to.be.deep.equal(tx);
+    });
   });
+});
 
   describe('#getSignedDigest()', () => {
     it('should throw an error when chain ID is not specified', async () => {