Fix missing exception check in typed array constructor.

src/d8.cc

Index: src/d8.cc
diff --git a/src/d8.cc b/src/d8.cc
index 8233f861ea46c85dc344e83e61c4539a4fac5694..83e2fc50d5d43db6290b9e7808313d6806ebe97a 100644
--- a/src/d8.cc
+++ b/src/d8.cc
@@ -532,8 +532,9 @@ Handle<Value> Shell::CreateExternalArray(const Arguments& args,
     if (args[0]->IsObject() &&
         args[0]->ToObject()->Has(Symbols::length(isolate))) {
       // Construct from array.
-      length = convertToUint(
-          args[0]->ToObject()->Get(Symbols::length(isolate)), &try_catch);
+      Local<Value> value = args[0]->ToObject()->Get(Symbols::length(isolate));
+      if (try_catch.HasCaught()) return try_catch.ReThrow();
+      length = convertToUint(value, &try_catch);
       if (try_catch.HasCaught()) return try_catch.ReThrow();
       init_from_array = true;
     } else {