chore: change option void value to be null

chore: update option void value to null

Author: Ryang-21

test/e2e/src/test-custom-types.js

@@ -247,7 +247,7 @@ describe("Custom Types Tests", function () {
     expect(response.result).to.equal(1);
 
     response = await this.context.client.option({ option: undefined });
-    expect(response.result).to.equal(undefined);
+    expect(response.result).to.equal(null);
     // this is the behavior we probably want, but fails
     // t.deepEqual(await t.context.client.option(), undefined) // typing and implementation require the object
     // t.deepEqual((await t.context.client.option({})).result, undefined) // typing requires argument; implementation would be fine with this

test/unit/spec/contract_spec.ts

@@ -243,16 +243,16 @@ describe("Can round trip custom types", function () {
 
   it("option", () => {
     roundtrip("option", 1);
-    roundtrip("option", undefined);
+    roundtrip("option", null);
 
     roundtrip("option_struct", { a: 0, b: true, c: "hello" });
-    roundtrip("option_struct", undefined);
+    roundtrip("option_struct", null);
 
     roundtrip("option_option_struct", { a: 0, b: true, c: "hello" });
-    roundtrip("option_option_struct", undefined);
+    roundtrip("option_option_struct", null);
 
     roundtrip("option_vec_struct", [{ a: 0, b: true, c: "hello" }]);
-    roundtrip("option_vec_struct", undefined);
+    roundtrip("option_vec_struct", null);
   });
 
   it("u256", () => {