[ddc] Add back nullcheck in js_array

sigmundch · commit-bot@chromium.org · commit 9f4769fd3046 · 2020-02-12T19:01:03.000Z
Change-Id: I9c32705b97c54b47f03898f0d007a3f07b13e465 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/135358 Reviewed-by: Nicholas Shahan <nshahan@google.com> Commit-Queue: Sigmund Cherem <sigmund@google.com>
diff --git a/sdk_nnbd/lib/_internal/js_dev_runtime/private/js_array.dart b/sdk_nnbd/lib/_internal/js_dev_runtime/private/js_array.dart
@@ -552,7 +552,8 @@ class JSArray<E> implements List<E>, JSIndexable<E> {
 
   E operator [](int index) {
     // Suppress redundant null checks via JS.
-    if (JS<int>('!', '#', index) >= JS<int>('!', '#.length', this) ||
+    if (index == null ||
+        JS<int>('!', '#', index) >= JS<int>('!', '#.length', this) ||
         JS<int>('!', '#', index) < 0) {
       throw diagnoseIndexError(this, index);
     }
@@ -561,7 +562,8 @@ class JSArray<E> implements List<E>, JSIndexable<E> {
 
   void operator []=(int index, E value) {
     checkMutable('indexed set');
-    if (JS<int>('!', '#', index) >= JS<int>('!', '#.length', this) ||
+    if (index == null ||
+        JS<int>('!', '#', index) >= JS<int>('!', '#.length', this) ||
         JS<int>('!', '#', index) < 0) {
       throw diagnoseIndexError(this, index);
     }
