types error with options watch

Version

2.7.10

Reproduction link

codesandbox.io

Steps to reproduce

export default {
  name: "App",
  watch: {
    e: [
      "handle1",
      function handle2(val, oldVal) {},
      {
        handler: function handle3(val, oldVal) {},
      },
    ],
  },
};

What is expected?

no type error

What is actually happening?

type error