fix: don't interact with res if refresh has happened

[danielroe]

Description

In a server context we're getting this error:

Error [ERR_STREAM_WRITE_AFTER_END]: write after end
    at writeAfterEnd (_http_outgoing.js:694:15)
    at ServerResponse.end (_http_outgoing.js:815:7)
    at Timeout._onTimeout (/myproject/node_modules/vite/dist/node/chunks/dep-f2b4ca46.js:66784:21)
    at listOnTimeout (internal/timers.js:557:17)
    at processTimers (internal/timers.js:500:7) {
  code: 'ERR_STREAM_WRITE_AFTER_END'
}

It occurs when making a first SSR request when the vite cache dir is empty.

It seems the issue stems from this timeout getting called and trying to interact with a consumed node response. It seems that it would be possible simply to check whether a response has already been sent before responding.

What is the purpose of this pull request?

• Bug fix

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[patak-dev]

Looks like request.writeableEnded was added in v12.9.0. Is there a way to do this work from node v12?

[Shinigami92]

Looks like request.writeableEnded was added in v12.9.0. Is there a way to do this work from node v12?

I would count v12.9 as v12
I hope no-one needs a pre v12.9 today

[patak-dev]

We are about to bump the node version to v12.2 with this PR from @sodatea #4279 (comment), we could require v12.9 but this PR then needs to state that in engines and we should queue this one for the next minor, no?

[danielroe]

This PR is backwards compatible - behaviour won't change on Node < 12.9. But on 12.9+ it will prevent the error described in the text.