Mutation not recognized when imported with mapMutations next to other methods

[ntraut]

• [x ] I have searched through existing issues
• [x ] I have read through docs
• [x ] I have read FAQ
• [x ] I have tried restarting VS Code or running Vetur: Restart VLS

Info

• Platform: Win
• Vetur version: 0.31.3
• VS Code version: 1.52.1

Problem

I try to import a mutation with the method ...mapMutations. If this is the only method in my vue file can use it without any warning. I have this in my script section:

  methods: {
    ...mapMutations(['increment'])
  }

and this in my template section:

<button @click="increment">X</button>

But if I add another method which is independent from my initial method:

  methods: {
    method2() {
      console.log('method2')
    },
    ...mapMutations(['increment'])
  }

I get the following error in my template:

Property 'increment' does not exist on type 'CombinedVueInstance<{ method2(): void; } & Record<never, any> & Vue, object, object, object, Record<never, any>>'.

The vue app is still working, I only get the error in vscode.

Reproducible Case

I did a minimal example starting from vue hello world:
https://github.com/ntraut/vue-hello-world

[yoyo930021]

It's a type limit in Vuex.

Ref:
vuejs/vuex#1417
vuejs/vuex#1121

[yoyo930021]

Temporarily open issue to confirm.

[ntraut]

This problem is too complicated for I can understand it fully but what seems strange to me is that if there is only ...mapMutations we don't get any warning: even if we type the wrong name, vs code tells increment0 is a mutation method. But if we add another method with no link we get the warning.

In my opinion the warning should occur either in both cases or none of them...