[Bug Report] `[vuex] unknown action type: wait/start` occurred on Vue TypeScript

# Step to reproduce
Using `store.dispatch('wait/start', 'app loading', { root: true })` or `wait/end` on `router.beforeEach` in Vue TypeScript project.

However, it is working fine on Vue with CommonJS project.

# Expected Behavior
It should be worked without any error or warning.

# Actual Behavior
There have error for unknown action type.

```
[vuex] unknown action type: wait/start
```

# Environment
- **vue**: 2.6.11
- **vue-wait**: 1.4.8
- **typescript**: 3.8.3