Ensure error objects are propagated without modification (#1920)

* Ensure AggregateError is propagated without modification

* Update test to not rely on AggregateError global

* Update lib/asyncify.js

Co-authored-by: Alex Early <alexander.early@gmail.com>

* Update .eslintrc.json to use es2021 globals

---------

Co-authored-by: Alex Early <alexander.early@gmail.com>

.eslintrc.json

@@ -2,7 +2,7 @@
     "env": {
         "browser": true,
         "node": true,
-        "es6": "es2021"
+        "es2021": true
     },
     "parser": "@babel/eslint-parser",
     "parserOptions": {

lib/asyncify.js

@@ -87,7 +87,7 @@ function handlePromise(promise, callback) {
     return promise.then(value => {
         invokeCallback(callback, null, value);
     }, err => {
-        invokeCallback(callback, err && err.message ? err : new Error(err));
+        invokeCallback(callback, err && (err instanceof Error || err.message) ? err : new Error(err));
     });
 }
 

test/asyncify.js

@@ -59,6 +59,22 @@ describe('asyncify', () => {
         }
     });
 
+    it('propagates error with empty message without modification', (done) => {
+        let originalErr;
+        async.asyncify(async () => {
+            originalErr = new AggregateError([new Error('foo'), new Error('bar')]);
+            throw originalErr;
+        })((err) => {
+            assert(err);
+            assert.strictEqual(err, originalErr);
+            expect(err.errors).to.be.an('array');
+            expect(err.errors.length).to.equal(2);
+            expect(err.errors[0].message).to.equal('foo');
+            expect(err.errors[1].message).to.equal('bar');
+            done();
+        })
+    })
+
     describe('promisified', () => {
         function promisifiedTests(Promise) {
             it('resolve', (done) => {