In notify, why is the return not checked when subs is empty

### Version
2.7.14

### Reproduction link
[github.com](https://github.com/vuejs/vue/blob/main/src/core/observer/dep.ts)







### Steps to reproduce
There is no

### What is expected?
const subs = this.subs.filter(s => s) as DepTarget[]
if (subs.length === 0) return

### What is actually happening?
subs Keep running down