!5640 API modify, adapt DefaultApplication testcase

Merge pull request !5640 from SoftSquirrel/master

bundlemanager/bundle_standard/bundlemanager/actsbundlemanageretstest/entry/src/main/ets/test/IsDefaultApplication.test.ets

@@ -32,7 +32,7 @@ export default function isDefaultApplicationTest() {
                   console.info("isDefaultApplication_0100 data--- " + data)
                   console.info("isDefaultApplication_0100 err--- " + err)
                   expect(data).assertFalse()
-                  expect(err).assertEqual(0)
+                  expect(err).assertEqual(null)
                   done()
               })
           });