HTTP Trailers advertised in Response type but unavailable in runtime

[aaronhuggins]

I was investigating the use of HTTP trailers but I've found that they are not implemented in the runtime.

The feature exists in types here:

deno/ext/fetch/lib.deno_fetch.d.ts

Line 424 in 7c3df66

readonly trailer: Promise<Headers>;

Reproduction example:

const res = await fetch('https://reqres.in/api/users/2')
const trailers = await res.trailer
console.log(trailers.has('what'))

Suggestion:
Remove the class member until it has been implemented; alternatively, throw a more explanatory error indicating implementation status.