events: show inspected error in uncaught 'error' message

If there is no handler for `.emit('error', value)` and `value`
is not an `Error` object, we currently just call `.toString()`
on it.

Almost always, using `util.inspect()` provides better information
for diagnostic purposes, so prefer to use that instead.

Refs: https://github.com/nodejs/help/issues/1729

PR-URL: https://github.com/nodejs/node/pull/25621
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Matheus Marchini <mat@mmarchini.me>

1 files changed, 14 insertions, 1 deletions

diff --git a/test/parallel/test-event-emitter-errors.js b/test/parallel/test-event-emitter-errors.js
index ef2bbee93f..13d3a98d9c 100644
--- a/test/parallel/test-event-emitter-errors.js
+++ b/test/parallel/test-event-emitter-errors.js
@@ -1,6 +1,7 @@
 'use strict';
 const common = require('../common');
 const EventEmitter = require('events');
+const util = require('util');
 
 const EE = new EventEmitter();
 
@@ -9,7 +10,7 @@ common.expectsError(
   {
     code: 'ERR_UNHANDLED_ERROR',
     type: Error,
-    message: 'Unhandled error. (Accepts a string)'
+    message: "Unhandled error. ('Accepts a string')"
   }
 );
 
@@ -18,6 +19,18 @@ common.expectsError(
   {
     code: 'ERR_UNHANDLED_ERROR',
     type: Error,
+    message: "Unhandled error. ({ message: 'Error!' })"
+  }
+);
+
+common.expectsError(
+  () => EE.emit('error', {
+    message: 'Error!',
+    [util.inspect.custom]() { throw new Error(); }
+  }),
+  {
+    code: 'ERR_UNHANDLED_ERROR',
+    type: Error,
     message: 'Unhandled error. ([object Object])'
   }
 );