Inconsistent types for agent option

[sleroq]

Describe the bug

• Node.js version: 18.15.0
• Typescript version: 5.0.4
• OS & version: NixOS 22.11.3889.f5364316e31 (Raccoon) x86_64

I noticed that the type definition for the agent option allows undefined as a valid value, but when I pass undefined at runtime, I get an error saying that agent value is expected to be an object.

Actual behavior

➜  testing-got tsc && node dist/index.js
node:internal/process/esm_loader:97
    internalBinding('errors').triggerUncaughtException(
                              ^

RequestError: Expected value which is `plain object`, received value of type `undefined`.
    at Request._destroy (file:///home/sleroq/develop/other/testing-got/node_modules/got/dist/source/core/index.js:481:21)
    at _destroy (node:internal/streams/destroy:109:10)
    at Request.destroy (node:internal/streams/destroy:71:5)
    at Request.flush (file:///home/sleroq/develop/other/testing-got/node_modules/got/dist/source/core/index.js:240:22)
    at lastHandler (file:///home/sleroq/develop/other/testing-got/node_modules/got/dist/source/create.js:37:26)
    at iterateHandlers (file:///home/sleroq/develop/other/testing-got/node_modules/got/dist/source/create.js:49:28)
    at got (file:///home/sleroq/develop/other/testing-got/node_modules/got/dist/source/create.js:69:16)
    at file:///home/sleroq/develop/other/testing-got/dist/index.js:2:7
    at assertType (file:///home/sleroq/develop/other/testing-got/node_modules/@sindresorhus/is/dist/index.js:305:15)
    at Object.plainObject (file:///home/sleroq/develop/other/testing-got/node_modules/@sindresorhus/is/dist/index.js:377:29)
    at set agent [as agent] (file:///home/sleroq/develop/other/testing-got/node_modules/got/dist/source/core/options.js:461:16)
    at Options.merge (file:///home/sleroq/develop/other/testing-got/node_modules/got/dist/source/core/options.js:411:27)
    at new Options (file:///home/sleroq/develop/other/testing-got/node_modules/got/dist/source/core/options.js:355:26)
    at new Request (file:///home/sleroq/develop/other/testing-got/node_modules/got/dist/source/core/index.js:224:28)
    at got (file:///home/sleroq/develop/other/testing-got/node_modules/got/dist/source/create.js:31:25)
    at file:///home/sleroq/develop/other/testing-got/dist/index.js:2:7
    at ModuleJob.run (node:internal/modules/esm/module_job:194:25) {

Expected behavior

I expected the code to run without any errors and print the response body from example.com.

Code to reproduce

import got from 'got';

await got('https://example.com', {
    agent: undefined,
})

Checklist

• I have read the documentation.
• I have tried my code with the latest version of Node.js and Got.