improve error serialization compat

lib/err-helpers.js

@@ -5,9 +5,13 @@
 // * Please upstream improvements there                         *
 // **************************************************************
 
+const isErrorLike = (err) => {
+  return err && typeof err.message === 'string'
+}
+
 /**
  * @param {Error|{ cause?: unknown|(()=>err)}} err
- * @returns {Error|undefined}
+ * @returns {Error|Object|undefined}
  */
 const getErrorCause = (err) => {
   if (!err) return
@@ -21,11 +25,11 @@ const getErrorCause = (err) => {
     // @ts-ignore
     const causeResult = err.cause()
 
-    return causeResult instanceof Error
+    return isErrorLike(causeResult)
       ? causeResult
       : undefined
   } else {
-    return cause instanceof Error
+    return isErrorLike(cause)
       ? cause
       : undefined
   }
@@ -40,7 +44,7 @@ const getErrorCause = (err) => {
  * @returns {string}
  */
 const _stackWithCauses = (err, seen) => {
-  if (!(err instanceof Error)) return ''
+  if (!isErrorLike(err)) return ''
 
   const stack = err.stack || ''
 
@@ -75,7 +79,7 @@ const stackWithCauses = (err) => _stackWithCauses(err, new Set())
  * @returns {string}
  */
 const _messageWithCauses = (err, seen, skip) => {
-  if (!(err instanceof Error)) return ''
+  if (!isErrorLike(err)) return ''
 
   const message = skip ? '' : (err.message || '')
 
@@ -107,6 +111,7 @@ const _messageWithCauses = (err, seen, skip) => {
 const messageWithCauses = (err) => _messageWithCauses(err, new Set())
 
 module.exports = {
+  isErrorLike,
   getErrorCause,
   stackWithCauses,
   messageWithCauses

lib/err.js

@@ -2,7 +2,7 @@
 
 module.exports = errSerializer
 
-const { messageWithCauses, stackWithCauses } = require('./err-helpers')
+const { messageWithCauses, stackWithCauses, isErrorLike } = require('./err-helpers')
 
 const { toString } = Object.prototype
 const seen = Symbol('circular-ref-tag')
@@ -44,7 +44,7 @@ Object.defineProperty(pinoErrProto, rawSymbol, {
 })
 
 function errSerializer (err) {
-  if (!(err instanceof Error)) {
+  if (!isErrorLike(err)) {
     return err
   }
 
@@ -56,14 +56,14 @@ function errSerializer (err) {
   _err.message = messageWithCauses(err)
   _err.stack = stackWithCauses(err)
 
-  if (global.AggregateError !== undefined && err instanceof global.AggregateError && Array.isArray(err.errors)) {
+  if (Array.isArray(err.errors)) {
     _err.aggregateErrors = err.errors.map(err => errSerializer(err))
   }
 
   for (const key in err) {
     if (_err[key] === undefined) {
       const val = err[key]
-      if (val instanceof Error) {
+      if (isErrorLike(val)) {
         // We append cause messages and stacks to _err, therefore skipping causes here
         if (key !== 'cause' && !Object.prototype.hasOwnProperty.call(val, seen)) {
           _err[key] = errSerializer(val)

test/err.test.js

@@ -47,18 +47,23 @@ test('serializes nested errors', function (t) {
 })
 
 test('serializes error causes', function (t) {
-  t.plan(7)
-  const err = Error('foo')
-  err.cause = Error('bar')
-  err.cause.cause = Error('abc')
-  const serialized = serializer(err)
-  t.equal(serialized.type, 'Error')
-  t.equal(serialized.message, 'foo: bar: abc')
-  t.match(serialized.stack, /err\.test\.js:/)
-  t.match(serialized.stack, /Error: foo/)
-  t.match(serialized.stack, /Error: bar/)
-  t.match(serialized.stack, /Error: abc/)
-  t.notOk(serialized.cause)
+  t.plan(14)
+  for (const cause of [
+    Error('bar'),
+    { message: 'bar', stack: 'Error: bar: err.test.js:' }
+  ]) {
+    const err = Error('foo')
+    err.cause = cause
+    err.cause.cause = Error('abc')
+    const serialized = serializer(err)
+    t.equal(serialized.type, 'Error')
+    t.equal(serialized.message, 'foo: bar: abc')
+    t.match(serialized.stack, /err\.test\.js:/)
+    t.match(serialized.stack, /Error: foo/)
+    t.match(serialized.stack, /Error: bar/)
+    t.match(serialized.stack, /Error: abc/)
+    t.notOk(serialized.cause)
+  }
 })
 
 test('serializes error causes with VError support', function (t) {
@@ -161,7 +166,7 @@ test('redefined err.constructor doesnt crash serializer', function (t) {
   check(serializer(err5), 'Error')
 })
 
-test('pass through anything that is not an Error', function (t) {
+test('pass through anything that does not look like an Error', function (t) {
   t.plan(3)
 
   function check (a) {
@@ -191,18 +196,20 @@ test('can wrap err serializers', function (t) {
 })
 
 test('serializes aggregate errors', { skip: !global.AggregateError }, function (t) {
-  t.plan(8)
+  t.plan(14)
   const foo = new Error('foo')
   const bar = new Error('bar')
-  const aggregate = new AggregateError([foo, bar], 'aggregated message') // eslint-disable-line no-undef
-
-  const serialized = serializer(aggregate)
-  t.equal(serialized.type, 'AggregateError')
-  t.equal(serialized.message, 'aggregated message')
-  t.equal(serialized.aggregateErrors.length, 2)
-  t.equal(serialized.aggregateErrors[0].message, 'foo')
-  t.equal(serialized.aggregateErrors[1].message, 'bar')
-  t.match(serialized.aggregateErrors[0].stack, /^Error: foo/)
-  t.match(serialized.aggregateErrors[1].stack, /^Error: bar/)
-  t.match(serialized.stack, /err\.test\.js:/)
+  for (const aggregate of [
+    new AggregateError([foo, bar], 'aggregated message'), // eslint-disable-line no-undef
+    { errors: [foo, bar], message: 'aggregated message', stack: 'err.test.js:' }
+  ]) {
+    const serialized = serializer(aggregate)
+    t.equal(serialized.message, 'aggregated message')
+    t.equal(serialized.aggregateErrors.length, 2)
+    t.equal(serialized.aggregateErrors[0].message, 'foo')
+    t.equal(serialized.aggregateErrors[1].message, 'bar')
+    t.match(serialized.aggregateErrors[0].stack, /^Error: foo/)
+    t.match(serialized.aggregateErrors[1].stack, /^Error: bar/)
+    t.match(serialized.stack, /err\.test\.js:/)
+  }
 })