From cb56e9f3344b33eab7a0145b81e0604f29daa5bf Mon Sep 17 00:00:00 2001
From: Pelle Wessman <pelle@kodfabrik.se>
Date: Mon, 13 Jun 2022 15:39:22 +0200
Subject: [PATCH 1/5] Revert "Nested VError causes (#108)"

This reverts commit 5b88f7ee2597a035eb935b3d172bd3791f2c08db.
---
 lib/err-helpers.js | 30 +++++++++++++++---------------
 lib/err.js         |  5 ++---
 test/err.test.js   | 28 ----------------------------
 3 files changed, 17 insertions(+), 46 deletions(-)

diff --git a/lib/err-helpers.js b/lib/err-helpers.js
index d00c201..17b465f 100644
--- a/lib/err-helpers.js
+++ b/lib/err-helpers.js
@@ -12,22 +12,23 @@
 const getErrorCause = (err) => {
   if (!err) return
 
-  const cause = evaluateCause(err.cause)
+  /** @type {unknown} */
+  // @ts-ignore
+  const cause = err.cause
 
-  return cause instanceof Error
-    ? cause
-    : undefined
-}
+  // VError / NError style causes
+  if (typeof cause === 'function') {
+    // @ts-ignore
+    const causeResult = err.cause()
 
-/**
- * @param {unknown|(()=>err)} cause
- * @returns {Error|undefined}
- */
-const evaluateCause = (cause) => {
-  // VError / NError style causes are functions
-  return typeof cause === 'function'
-    ? cause()
-    : cause
+    return causeResult instanceof Error
+      ? causeResult
+      : undefined
+  } else {
+    return cause instanceof Error
+      ? cause
+      : undefined
+  }
 }
 
 /**
@@ -107,7 +108,6 @@ const messageWithCauses = (err) => _messageWithCauses(err, new Set())
 
 module.exports = {
   getErrorCause,
-  evaluateCause,
   stackWithCauses,
   messageWithCauses
 }
diff --git a/lib/err.js b/lib/err.js
index fd63e23..d92fce4 100644
--- a/lib/err.js
+++ b/lib/err.js
@@ -2,7 +2,7 @@
 
 module.exports = errSerializer
 
-const { messageWithCauses, stackWithCauses, evaluateCause } = require('./err-helpers')
+const { messageWithCauses, stackWithCauses } = require('./err-helpers')
 
 const { toString } = Object.prototype
 const seen = Symbol('circular-ref-tag')
@@ -66,8 +66,7 @@ function errSerializer (err) {
   }
 
   if (err.cause) {
-    const cause = evaluateCause(err.cause)
-    _err.cause = errSerializer(cause)
+    _err.cause = errSerializer(err.cause)
   }
 
   for (const key in err) {
diff --git a/test/err.test.js b/test/err.test.js
index 0ca4a58..d073c06 100644
--- a/test/err.test.js
+++ b/test/err.test.js
@@ -218,31 +218,3 @@ test('serializes causes', function (t) {
   t.equal(serialized.cause.cause.message, 'baz')
   t.match(serialized.cause.cause.stack, /err\.test\.js:/)
 })
-
-test('serializes causes with VError support', function (t) {
-  t.plan(11)
-
-  // Fake VError-style setup
-  const err = Error('foo: bar')
-  err.cause = () => {
-    const err = Error('bar')
-    err.cause = Error('abc')
-    return err
-  }
-
-  const serialized = serializer(err)
-
-  t.equal(serialized.type, 'Error')
-  t.equal(serialized.message, 'foo: bar: abc') // message serialization already walks cause-chain
-  t.match(serialized.stack, /err\.test\.js:/)
-
-  t.ok(serialized.cause)
-  t.equal(serialized.cause.type, 'Error')
-  t.equal(serialized.cause.message, 'bar: abc')
-  t.match(serialized.cause.stack, /err\.test\.js:/)
-
-  t.ok(serialized.cause.cause)
-  t.equal(serialized.cause.cause.type, 'Error')
-  t.equal(serialized.cause.cause.message, 'abc')
-  t.match(serialized.cause.cause.stack, /err\.test\.js:/)
-})

From 23f62f2e0bc216f794bbbd1baef2941fd9918639 Mon Sep 17 00:00:00 2001
From: Pelle Wessman <pelle@kodfabrik.se>
Date: Mon, 13 Jun 2022 15:39:32 +0200
Subject: [PATCH 2/5] Revert "Serialize errors with cause (#105)"

This reverts commit ae8395628a7520e8434106a08cfebb7cc44f5b29.
---
 lib/err.js       |  9 ---------
 test/err.test.js | 24 ------------------------
 2 files changed, 33 deletions(-)

diff --git a/lib/err.js b/lib/err.js
index d92fce4..ccd81c9 100644
--- a/lib/err.js
+++ b/lib/err.js
@@ -28,11 +28,6 @@ const pinoErrProto = Object.create({}, {
     writable: true,
     value: undefined
   },
-  cause: {
-    enumerable: true,
-    writable: true,
-    value: undefined
-  },
   raw: {
     enumerable: false,
     get: function () {
@@ -65,10 +60,6 @@ function errSerializer (err) {
     _err.aggregateErrors = err.errors.map(err => errSerializer(err))
   }
 
-  if (err.cause) {
-    _err.cause = errSerializer(err.cause)
-  }
-
   for (const key in err) {
     if (_err[key] === undefined) {
       const val = err[key]
diff --git a/test/err.test.js b/test/err.test.js
index d073c06..746ed7a 100644
--- a/test/err.test.js
+++ b/test/err.test.js
@@ -194,27 +194,3 @@ test('serializes aggregate errors', { skip: !global.AggregateError }, function (
   t.match(serialized.aggregateErrors[1].stack, /^Error: bar/)
   t.match(serialized.stack, /err\.test\.js:/)
 })
-
-test('serializes causes', function (t) {
-  t.plan(11)
-
-  const bar = new Error('bar')
-  bar.cause = new Error('foo')
-  bar.cause.cause = new Error('baz')
-
-  const serialized = serializer(bar)
-
-  t.equal(serialized.type, 'Error')
-  t.equal(serialized.message, 'bar: foo: baz') // message serialization already walks cause-chain
-  t.match(serialized.stack, /err\.test\.js:/)
-
-  t.ok(serialized.cause)
-  t.equal(serialized.cause.type, 'Error')
-  t.equal(serialized.cause.message, 'foo: baz')
-  t.match(serialized.cause.stack, /err\.test\.js:/)
-
-  t.ok(serialized.cause.cause)
-  t.equal(serialized.cause.cause.type, 'Error')
-  t.equal(serialized.cause.cause.message, 'baz')
-  t.match(serialized.cause.cause.stack, /err\.test\.js:/)
-})

From 8fd180977db2037b2820e8cd5b314bb6be4882c9 Mon Sep 17 00:00:00 2001
From: Pelle Wessman <pelle@kodfabrik.se>
Date: Mon, 13 Jun 2022 15:42:22 +0200
Subject: [PATCH 3/5] Never serialize `.cause` when an `Error`

Instead rely on its content being appended to the message and the stack.

This is an alternative fix to #94, replacing #105 and #108 + makes #109 not needed
---
 lib/err.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/err.js b/lib/err.js
index ccd81c9..764e2e4 100644
--- a/lib/err.js
+++ b/lib/err.js
@@ -63,9 +63,9 @@ function errSerializer (err) {
   for (const key in err) {
     if (_err[key] === undefined) {
       const val = err[key]
-      if (val instanceof Error && key !== 'cause') {
+      if (val instanceof Error) {
         /* eslint-disable no-prototype-builtins */
-        if (!val.hasOwnProperty(seen)) {
+        if (key !== 'cause' && !val.hasOwnProperty(seen)) {
           _err[key] = errSerializer(val)
         }
       } else {

From d848f45c82c7c858a13bf064ba313d2b799d5478 Mon Sep 17 00:00:00 2001
From: Pelle Wessman <pelle@kodfabrik.se>
Date: Mon, 13 Jun 2022 16:35:21 +0200
Subject: [PATCH 4/5] Add tests

---
 test/err.test.js | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/test/err.test.js b/test/err.test.js
index 746ed7a..00a54d6 100644
--- a/test/err.test.js
+++ b/test/err.test.js
@@ -47,7 +47,7 @@ test('serializes nested errors', function (t) {
 })
 
 test('serializes error causes', function (t) {
-  t.plan(6)
+  t.plan(7)
   const err = Error('foo')
   err.cause = Error('bar')
   err.cause.cause = Error('abc')
@@ -58,15 +58,17 @@ test('serializes error causes', function (t) {
   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) {
   t.plan(6)
   // Fake VError-style setup
   const err = Error('foo: bar')
-  err.cause = () => {
+  err.foo = 'abc'
+  err.cause = function () {
     const err = Error('bar')
-    err.cause = Error('abc')
+    err.cause = Error(this.foo)
     return err
   }
   const serialized = serializer(err)
@@ -78,6 +80,16 @@ test('serializes error causes with VError support', function (t) {
   t.match(serialized.stack, /Error: abc/)
 })
 
+test('keeps non-error cause', function (t) {
+  t.plan(3)
+  const err = Error('foo')
+  err.cause = 'abc'
+  const serialized = serializer(err)
+  t.equal(serialized.type, 'Error')
+  t.equal(serialized.message, 'foo')
+  t.equal(serialized.cause, 'abc')
+})
+
 test('prevents infinite recursion', function (t) {
   t.plan(4)
   const err = Error('foo')

From e785720c0b4a9a675cbf69e5865e800f9c62f32e Mon Sep 17 00:00:00 2001
From: Pelle Wessman <pelle@kodfabrik.se>
Date: Mon, 13 Jun 2022 22:28:52 +0200
Subject: [PATCH 5/5] Add explainer comment

---
 lib/err.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/err.js b/lib/err.js
index 764e2e4..c957394 100644
--- a/lib/err.js
+++ b/lib/err.js
@@ -64,8 +64,8 @@ function errSerializer (err) {
     if (_err[key] === undefined) {
       const val = err[key]
       if (val instanceof Error) {
-        /* eslint-disable no-prototype-builtins */
-        if (key !== 'cause' && !val.hasOwnProperty(seen)) {
+        // 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)
         }
       } else {