store.subscribeAction is not a function

[davestewart]

Version

6.0.3

Browser and OS info

Chrome 98

Steps to reproduce

Set a property $store on the Vue prototype:

Vue.prototype.$store = {}

What is expected?

I should be able to use a custom store without DevTools erroring

What is actually happening?

VueDevtools assumes this is a Vuex store (with subscribeAction) and this error appears when the page loads:

TypeError: store.subscribeAction is not a function
    at backend.js:4836:13
    at addPlugin (backend.js:2810:7)
    at async Object.<anonymous> (backend.js:2016:5)

---

I can add a no-op and it's fine, but I don't think devtools should be making assumptions about what $store may be in my app.

[davestewart]

I can submit a PR if easier, but likely one likely of code...