fix: unhandledrejection handling for sync throw in top level (#15279)

Fixes an edge in "unhandledrejection" event that prevent synchronous
errors being surfaced when throw from a top-level scope.

3 files changed, 17 insertions, 0 deletions

diff --git a/cli/tests/integration/run_tests.rs b/cli/tests/integration/run_tests.rs
index 25d84ae46..29e424aae 100644
--- a/cli/tests/integration/run_tests.rs
+++ b/cli/tests/integration/run_tests.rs
@@ -2787,3 +2787,8 @@ itest!(unhandled_rejection {
   args: "run --check unhandled_rejection.ts",
   output: "unhandled_rejection.ts.out",
 });
+
+itest!(unhandled_rejection_sync_error {
+  args: "run --check unhandled_rejection_sync_error.ts",
+  output: "unhandled_rejection_sync_error.ts.out",
+});
diff --git a/cli/tests/testdata/unhandled_rejection_sync_error.ts b/cli/tests/testdata/unhandled_rejection_sync_error.ts
new file mode 100644
index 000000000..0dabb1cb7
--- /dev/null
+++ b/cli/tests/testdata/unhandled_rejection_sync_error.ts
@@ -0,0 +1,6 @@
+globalThis.addEventListener("unhandledrejection", (e) => {
+  console.log("unhandled rejection at:", e.promise, "reason:", e.reason);
+  e.preventDefault();
+});
+
+throw new Error("boom!");
diff --git a/cli/tests/testdata/unhandled_rejection_sync_error.ts.out b/cli/tests/testdata/unhandled_rejection_sync_error.ts.out
new file mode 100644
index 000000000..270319824
--- /dev/null
+++ b/cli/tests/testdata/unhandled_rejection_sync_error.ts.out
@@ -0,0 +1,6 @@
+[WILDCARD]
+unhandled rejection at: Promise {
+  <rejected> Error: boom!
+    at file:///[WILDCARD]testdata/unhandled_rejection_sync_error.ts:6:7
+} reason: Error: boom!
+    at file:///[WILDCARD]testdata/unhandled_rejection_sync_error.ts:6:7