fix custom error arg

Author: Amxx

contracts/utils/Base64.sol

@@ -187,28 +187,28 @@ library Base64 {
                 // slither-disable-next-line incorrect-shift
                 if iszero(and(shl(a, 1), 0xffffffd0ffffffc47ff5)) {
                     mstore(0, errorSelector)
-                    mstore(4, add(a, 49))
+                    mstore(4, add(a, 43))
                     revert(0, 0x24)
                 }
                 let b := sub(byte(29, input), 43)
                 // slither-disable-next-line incorrect-shift
                 if iszero(and(shl(b, 1), 0xffffffd0ffffffc47ff5)) {
                     mstore(0, errorSelector)
-                    mstore(4, add(b, 49))
+                    mstore(4, add(b, 43))
                     revert(0, 0x24)
                 }
                 let c := sub(byte(30, input), 43)
                 // slither-disable-next-line incorrect-shift
                 if iszero(and(shl(c, 1), 0xffffffd0ffffffc47ff5)) {
                     mstore(0, errorSelector)
-                    mstore(4, add(c, 49))
+                    mstore(4, add(c, 43))
                     revert(0, 0x24)
                 }
                 let d := sub(byte(31, input), 43)
                 // slither-disable-next-line incorrect-shift
                 if iszero(and(shl(d, 1), 0xffffffd0ffffffc47ff5)) {
                     mstore(0, errorSelector)
-                    mstore(4, add(d, 49))
+                    mstore(4, add(d, 43))
                     revert(0, 0x24)
                 }
 

test/utils/Base64.test.js

@@ -51,12 +51,20 @@ describe('Base64', function () {
   });
 
   it('Decode invalid base64 string', async function () {
+    const helper = { interface: ethers.Interface.from(['error InvalidBase64Digit(uint8)']) };
+
     // ord('$') < 43
-    await expect(this.mock.$decode('dGVzd$==')).to.be.reverted;
+    await expect(this.mock.$decode('dGVzd$=='))
+      .to.be.revertedWithCustomError(helper, 'InvalidBase64Digit')
+      .withArgs('$'.charCodeAt(0));
     // ord('~') > 122
-    await expect(this.mock.$decode('dGVzd~==')).to.be.reverted;
+    await expect(this.mock.$decode('dGVzd~=='))
+      .to.be.revertedWithCustomError(helper, 'InvalidBase64Digit')
+      .withArgs('~'.charCodeAt(0));
     // ord('@') in range, but '@' not in the dictionary
-    await expect(this.mock.$decode('dGVzd@==')).to.be.reverted;
+    await expect(this.mock.$decode('dGVzd@=='))
+      .to.be.revertedWithCustomError(helper, 'InvalidBase64Digit')
+      .withArgs('@'.charCodeAt(0));
   });
 
   it('Encode reads beyond the input buffer into dirty memory', async function () {