change error value to bytes1

Author: arr00

contracts/utils/Base64.sol

@@ -11,7 +11,7 @@ import {SafeCast} from "./math/SafeCast.sol";
 library Base64 {
     using SafeCast for bool;
 
-    error InvalidBase64Digit(uint8);
+    error InvalidBase64Digit(bytes1);
 
     /**
      * @dev Converts a `bytes` to its Bytes64 `string` representation.
@@ -187,21 +187,21 @@ library Base64 {
                 // slither-disable-next-line incorrect-shift
                 if iszero(and(shl(a, 1), 0xffffffd0ffffffc47ff5)) {
                     mstore(0, errorSelector)
-                    mstore(4, add(a, 43))
+                    mstore(4, shl(248, 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, 43))
+                    mstore(4, shl(248, 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, 43))
+                    mstore(4, shl(248, add(c, 43)))
                     revert(0, 0x24)
                 }
                 let d := sub(byte(31, input), 43)

test/utils/Base64.test.js

@@ -51,20 +51,20 @@ describe('Base64', function () {
   });
 
   it('Decode invalid base64 string', async function () {
-    const helper = { interface: ethers.Interface.from(['error InvalidBase64Digit(uint8)']) };
+    const helper = { interface: ethers.Interface.from(['error InvalidBase64Digit(bytes1)']) };
 
     // ord('$') < 43
     await expect(this.mock.$decode('dGVzd$=='))
       .to.be.revertedWithCustomError(helper, 'InvalidBase64Digit')
-      .withArgs('$'.charCodeAt(0));
+      .withArgs(`0x${'$'.charCodeAt(0).toString(16)}`);
     // ord('~') > 122
     await expect(this.mock.$decode('dGVzd~=='))
       .to.be.revertedWithCustomError(helper, 'InvalidBase64Digit')
-      .withArgs('~'.charCodeAt(0));
+      .withArgs(`0x${'~'.charCodeAt(0).toString(16)}`);
     // ord('@') in range, but '@' not in the dictionary
     await expect(this.mock.$decode('dGVzd@=='))
       .to.be.revertedWithCustomError(helper, 'InvalidBase64Digit')
-      .withArgs('@'.charCodeAt(0));
+      .withArgs(`0x${'@'.charCodeAt(0).toString(16)}`);
   });
 
   it('Encode reads beyond the input buffer into dirty memory', async function () {