Fix updating errorKey with default error serializer (#1593)

lib/tools.js

@@ -20,6 +20,7 @@ const {
   nestedKeySym,
   formattersSym,
   messageKeySym,
+  errorKeySym,
   nestedKeyStrSym
 } = require('./symbols')
 const { isMainThread } = require('worker_threads')
@@ -97,6 +98,7 @@ function asJson (obj, msg, num, time) {
   const serializers = this[serializersSym]
   const formatters = this[formattersSym]
   const messageKey = this[messageKeySym]
+  const errorKey = this[errorKeySym]
   let data = this[lsCacheSym][num] + time
 
   // we need the child bindings added to the output first so instance logged
@@ -112,7 +114,11 @@ function asJson (obj, msg, num, time) {
   for (const key in obj) {
     value = obj[key]
     if (Object.prototype.hasOwnProperty.call(obj, key) && value !== undefined) {
-      value = serializers[key] ? serializers[key](value) : value
+      if (serializers[key]) {
+        value = serializers[key](value)
+      } else if (key === errorKey && serializers.err) {
+        value = serializers.err(value)
+      }
 
       const stringifier = stringifiers[key] || wildcardStringifier
 

test/errorKey.test.js

@@ -18,3 +18,17 @@ test('set the errorKey with error serializer', async ({ equal, same }) => {
   equal(o[errorKey].message, 'test')
   equal(typeof o[errorKey].stack, 'string')
 })
+
+test('set the errorKey without error serializer', async ({ equal, same }) => {
+  const stream = sink()
+  const errorKey = 'error'
+  const instance = pino({
+    errorKey
+  }, stream)
+  instance.error(new ReferenceError('test'))
+  const o = await once(stream, 'data')
+  equal(typeof o[errorKey], 'object')
+  equal(o[errorKey].type, 'ReferenceError')
+  equal(o[errorKey].message, 'test')
+  equal(typeof o[errorKey].stack, 'string')
+})