diff --git a/dom/workers/WorkerPrivate.cpp b/dom/workers/WorkerPrivate.cpp
index 01d7c8f63ad1..edd2960b9097 100644
--- a/dom/workers/WorkerPrivate.cpp
+++ b/dom/workers/WorkerPrivate.cpp
@@ -5927,7 +5927,11 @@ void WorkerPrivate::ReportError(JSContext* aCx,
   }
 
   JS::ExceptionStack exnStack(aCx);
-  if (JS_IsExceptionPending(aCx)) {
+  // NOTE: This function is used both for errors and warnings, and warnings
+  //       can be reported while there's a pending exception.
+  //       Warnings are always reported with non-null JSErrorReport.
+  if (!aReport || !aReport->isWarning()) {
+    MOZ_ASSERT(JS_IsExceptionPending(aCx));
     if (!JS::StealPendingExceptionStack(aCx, &exnStack)) {
       JS_ClearPendingException(aCx);
       return;
@@ -5941,10 +5945,6 @@ void WorkerPrivate::ReportError(JSContext* aCx,
       JSAutoRealm ar(aCx, stackGlobal);
       report->SerializeWorkerStack(aCx, this, stack);
     }
-  } else {
-    // ReportError is also used for reporting warnings,
-    // so there won't be a pending exception.
-    MOZ_ASSERT(aReport && aReport->isWarning());
   }
 
   if (report->mMessage.IsEmpty() && aToStringResult) {
diff --git a/dom/worklet/WorkletThread.cpp b/dom/worklet/WorkletThread.cpp
index f9452e7ec69e..bcddeeebe455 100644
--- a/dom/worklet/WorkletThread.cpp
+++ b/dom/worklet/WorkletThread.cpp
@@ -199,7 +199,11 @@ void WorkletJSContext::ReportError(JSErrorReport* aReport,
   RefPtr<AsyncErrorReporter> reporter = new AsyncErrorReporter(xpcReport);
 
   JSContext* cx = Context();
-  if (JS_IsExceptionPending(cx)) {
+  // NOTE: This function is used both for errors and warnings, and warnings
+  //       can be reported while there's a pending exception.
+  //       Warnings are always reported with non-null JSErrorReport.
+  if (!aReport || !aReport->isWarning()) {
+    MOZ_ASSERT(JS_IsExceptionPending(cx));
     JS::ExceptionStack exnStack(cx);
     if (JS::StealPendingExceptionStack(cx, &exnStack)) {
       JS::Rooted<JSObject*> stack(cx);