fix: require toUSVString from fetch utils

[Kikobeats]

Since util.toUSVString doesn't exist at node12, in this way the fallback implementation will be used.

[mcollina]

why this change?

[Kikobeats]

mainly to make webidl.converters.USVString addressable at Node12
https://github.com/vercel/edge-runtime/runs/7177696222?check_suite_focus=true#step%3A7%3A110=

[mcollina]

I'm a bit lost. None of fetch should run on v12.

[mcollina]

I'm a bit lost. None of fetch should run on v12.

[Rich-Harris]

Presently, undici's package.json specifies 12.18 as the minimum version:

undici/package.json

Lines 99 to 101 in 5ca25c2

	"engines": {
	"node": ">=12.18"
	},

In reality, it requires >16.9. Merging this PR wouldn't change that, since undici also uses Object.hasOwn. For that reason, I'd advocate updating the engines field and removing this line in favour of using the built-in util.toUSVString everywhere:

undici/lib/core/util.js

Line 385 in 5ca25c2

toUSVString: nodeUtil.toUSVString || ((val) => `${val}`),

[mcollina]

In reality, it requires >16.9.

Can you articulate? We have our suite testing everything on 12, minus fetch - which is v16+ and clearly documented as such.

I'd be happy to work on whatever incompatibility there is as long as I get a reproduction.

[mcollina]

I'd be happy to land this as long as we get a test that is failing on Node v12 - so we know we won't regress.

[Rich-Harris]

Sure — using Node 16.7:

const { Response } = require('undici');
new Response('ok');
/*
Uncaught TypeError: webidl.converters.USVString is not a function
    at Object.webidl.converters.XMLHttpRequestBodyInit (/[dir]/node_modules/undici/lib/fetch/response.js:516:30)
    at Object.webidl.converters.BodyInit (/[dir]/node_modules/undici/lib/fetch/response.js:554:28)
    at new Response (/[dir]/node_modules/undici/lib/fetch/response.js:138:32)
*/

Using Node 16.8:

const { Response } = require('undici');
new Response('ok');
/*
Uncaught TypeError: Object.hasOwn is not a function
    at Object.ResponseInit (/[dir]/node_modules/undici/lib/fetch/webidl.js:327:33)
    at new Response (/[dir]/node_modules/undici/lib/fetch/response.js:141:30)
*/

[mcollina]

If I understand it correctly: the whole of fetch() is available only in Node.js v16+ but we do not specify which minor anywhere, causing the problem at hand (and the fact we broke people using Node.js v16.7 vs 16.9). Is this correct?

@ronag do we want to support v16.7 at all? Our tests are currently failing there.

The issue at the top was mentioning Node.js v12, which is what took me off guard.

[KhafraDev]

do we want to support v16.7 at all?

Support should be easy enough, I don't see a reason not to. I'll work on a PR to support v16.5+ again.

[mcollina]

Just add 16.5.0 to CI so we don't regress again.

[Kikobeats]

closing since #1534 addressed it