Custom arrayMerger is never called and discards store state

[shugydw]

• vuex-persistedstate version: 3.1.0
• node version: v8.16.2
• yarn version: 1.22.4

What you did:

I am trying to build custom arrayMerger and put some if conditions. Based on it I would either merge or use store state or persisted state.

What happened:

The persisted state always takes over and discards the default store state.

Reproduction sandbox:

https://codesandbox.io/s/vuex-persistedstate-forked-izr4i

Problem description:

Custom arrayMerger is never invoked.

[shugydw]

Might be related to #293 as well!