Panic with npm:fetch-http2 when using headers with Uppercase characters

[arkei1]

Version: Deno 1.45.2

So, I got a panic when I tried to use http2 fetch like so:

import { fetch } from 'npm:fetch-http2'

const response = await fetch('https://google.com', {
  headers: {
    'User-Agent': 'fetch-http2'
  }
})

However such a code results in a panic:

$ deno run --allow-net main.ts

============================================================
Deno has panicked. This is a bug in Deno. Please report this
at https://github.com/denoland/deno/issues/new.
If you can reliably reproduce this panic, include the
reproduction steps and re-run with the RUST_BACKTRACE=1 env
var set and include the backtrace in your report.

Platform: linux x86_64
Version: 1.45.2
Args: ["deno", "run", "--allow-net", "main.ts"]

thread 'main' panicked at ext/node/ops/http2.rs:320:41:
called `Result::unwrap()` on an `Err` value: InvalidHeaderName
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

The error message refers to this line:

deno/ext/node/ops/http2.rs

Line 320 in 92abdb7

HeaderName::from_lowercase(&name).unwrap(),

Which uses from_lowercase from http crate:

https://github.com/hyperium/http/blob/f4e8c0c3159b18b8b7e4a6a3762c55528483d25a/src/header/name.rs#L1166-L1193

As seen from the function's code InvalidHeaderName can only occur if any of the characters is 0 according to HEADER_CHARS_H2 array:

https://github.com/hyperium/http/blob/f4e8c0c3159b18b8b7e4a6a3762c55528483d25a/src/header/name.rs#L1040-L1068

One might also notice that this array ain't got uppercase characters. That lead me to try a fully lowercase header:

import { fetch } from 'npm:fetch-http2'

const response = await fetch('https://google.com', {
  headers: {
    'user-agent': 'fetch-http2'
  }
})

And this works fine (it doesn't panic). I think the issue here is that deno uses a function intended for lowercase strings without ensuring that the string is indeed lowercase.