A question about uninitialized variables

Version

chakra-1_11_22

Test case

var h = function f(a0 = function () {
  a2;
}(), a2) {
};
h();

Execution steps

./ChakraCore/out/Debug/ch testcase.js

Output

Expected behavior

ReferenceError: can't access lexical declaration `a2' before initialization

Description

When executing this test case, a2 is not initialized before the call, other engines (such as v8, spiderMonkey, JavaScriptCore, etc.) threw a ReferenceError, but chakra did not do so. Is this a different implementation of chakra?