How to deal with the Property missing of ComponentPublicInstance?

[SSShooter]

Version

4.0.15

Reproduction link

codesandbox.io

Steps to reproduce

data() {
    return {
      isMounted: true,
    }
  },
beforeRouteEnter(to, from, next) {
    next((vm) => {
      if (to.meta.from.includes(from.path) || vm.isMounted) {
        vm.isMounted= false
        vm.fetch()
      }
    })
  }

What is expected?

Be able to access isMounted of vm

What is actually happening?

Property 'mount' does not exist on type 'ComponentPublicInstance<{}, {}, {}, {}, {}, {}, {}, {}, false, ComponentOptionsBase<any, any, any, any, any, any, any, any, any, {}>>'.

[posva]

Duplicate of #701