fix: DOMException doesn't throw on __callSitesEvals (#23729)

2 files changed, 13 insertions, 1 deletions

diff --git a/ext/web/01_dom_exception.js b/ext/web/01_dom_exception.js
index 9bab4881a..82e8f867f 100644
--- a/ext/web/01_dom_exception.js
+++ b/ext/web/01_dom_exception.js
@@ -167,7 +167,12 @@ ObjectDefineProperty(DOMException.prototype, "stack", {
 // hack doesn't apply. This patches it in.
 ObjectDefineProperty(DOMException.prototype, "__callSiteEvals", {
   get() {
-    return ArrayPrototypeSlice(this[_error].__callSiteEvals, 1);
+    // Call the stack getter so `__callSiteEvals` get populated.
+    this[_error].stack;
+    // To be extra sure, use an empty array if `__callSiteEvals` is still not there,
+    // eg. if the user overrides `Error.prepareStackTrace`.
+    const callSiteEvals = this[_error].__callSiteEvals ?? [];
+    return ArrayPrototypeSlice(callSiteEvals, 1);
   },
   configurable: true,
 });
diff --git a/tests/unit/dom_exception_test.ts b/tests/unit/dom_exception_test.ts
index de335e105..806248caa 100644
--- a/tests/unit/dom_exception_test.ts
+++ b/tests/unit/dom_exception_test.ts
@@ -1,6 +1,7 @@
 // Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
 
 import {
+  assert,
   assertEquals,
   assertNotEquals,
   assertStringIncludes,
@@ -21,3 +22,9 @@ Deno.test(function nameToCodeMappingPrototypeAccess() {
   assertNotEquals(newCode, new DOMException("test", "pollution").code);
   Reflect.deleteProperty(objectPrototype, "pollution");
 });
+
+Deno.test(function callSitesEvalsDoesntThrow() {
+  const e2 = new DOMException("asdf");
+  // @ts-ignore no types for `__callSiteEvals` but it's observable.
+  assert(Array.isArray(e2.__callSiteEvals));
+});