Improve customError testing (#4376)

test/helpers/customError.js

@@ -2,19 +2,19 @@ const { expect } = require('chai');
 
 /** Revert handler that supports custom errors. */
 async function expectRevertCustomError(promise, expectedErrorName, args) {
-  try {
-    await promise;
-    expect.fail("Expected promise to throw but it didn't");
-  } catch (revert) {
   if (!Array.isArray(args)) {
     expect.fail('Expected 3rd array parameter for error arguments');
   }
+
+  await promise.then(
+    () => expect.fail("Expected promise to throw but it didn't"),
+    ({ message }) => {
       // The revert message for custom errors looks like:
       // VM Exception while processing transaction:
       // reverted with custom error 'InvalidAccountNonce("0x70997970C51812dc3A010C7d01b50e0d17dc79C8", 0)'
 
       // We trim out anything inside the single quotes as comma-separated values
-    const [, error] = revert.message.match(/'(.*)'/);
+      const [, error] = message.match(/'(.*)'/);
 
       // Attempt to parse as an error
       const match = error.match(/(?<name>\w+)\((?<args>.*)\)/);
@@ -37,7 +37,8 @@ async function expectRevertCustomError(promise, expectedErrorName, args) {
 
       // Assert argument equality
       expect(sanitizedActual).to.have.members(sanitizedExpected, `Unexpected ${errorName} arguments`);
-  }
+    },
+  );
 }
 
 module.exports = {