Fix invalid array termination for null and undefined (#38)

* Add test case to check invalid terminator

* Fix invalid array termination

Author: kateinoigakukun

Diff for: IntegrationTests/TestSuites/Sources/PrimaryTests/main.swift

@@ -88,7 +88,7 @@ test("Array Iterator") {
     let prop_4 = getJSValue(this: globalObject1Ref, name: "prop_4")
     let array = try expectArray(prop_4)
     let expectedProp_4: [JSValue] = [
-        .number(3), .number(4), .string("str_elm_1"), .number(5),
+        .number(3), .number(4), .string("str_elm_1"), .null, .undefined, .number(5),
     ]
     try expectEqual(Array(array), expectedProp_4)
 }

Diff for: IntegrationTests/bin/primary-tests.js

@@ -5,7 +5,7 @@ global.globalObject1 = {
   "prop_2": 2,
   "prop_3": true,
   "prop_4": [
-    3, 4, "str_elm_1", 5,
+    3, 4, "str_elm_1", null, undefined, 5,
   ],
   "prop_5": {
     "func1": function () { return },
@@ -41,4 +41,4 @@ const { startWasiTask } = require("../lib")
 
 startWasiTask("./dist/PrimaryTests.wasm").catch(err => {
   console.log(err)
-});
+});

Diff for: Sources/JavaScriptKit/JSArrayRef.swift

@@ -34,7 +34,7 @@ extension JSArrayRef: RandomAccessCollection {
                 return nil
             }
             let value = ref[index]
-            return value.isNull ? nil : value
+            return value
         }
     }