Imagesharp: Image.Load() will throw ImageFormatException despite the image appearing to contain a proper data chunk

[QuantumToasted]

Prerequisites

• [x] I have written a descriptive issue title
• [x] I have verified that I am running the latest version of ImageSharp
• [ ] I have verified if the problem exist in both DEBUG and RELEASE mode
• [ ] I have searched open and closed issues to ensure it has not already been reported†

Description

Attempting to download a specific image to stream via an HttpClient and then loading it via Image.Load<Rgba32>() throws the following exception:

SixLabors.ImageSharp.ImageFormatException: PNG Image does not contain a data chunk

This is the first time this has ever occurred in my code, the exact method I have used to download and load images has never thrown this exception for the hundreds or maybe thousands of other images I and other users have used which called this method. I have asked a few friends to attempt to test this as well, and one other person did and did not report any issues, which makes this even stranger.

Steps to Reproduce

// ignore lack of using statements, I omitted them
var url = "https://cdn.discordapp.com/emojis/598551803566489611.png?v=1"
var response = await new HttpClient().GetAsync(url);
var stream = await response.Content.ReadAsStreamAsync();
var image = Image.Load<Rgba32>(stream); // throws on this line

Both downloading the image in a web browser AND writing stream directly to file produce a clean PNG image with what looks to be intact data chunks when opened with a tool like TweakPNG:

(I have essentially no knowledge of PNG headers, data chunks, etc, so if something here looks wrong then I do apologize. Take my knowledge with a grain of salt.)

System Configuration

• ImageSharp version: v1.0.0-unstable0806
• Other ImageSharp packages and versions: SixLabors.ImageSharp.Drawing v1.0.0-unstable0421
• Environment (Operating system, version and so on): Visual Studio 2019 16.4.4, Windows 10 x64
• .NET Framework version: .NET Core 3.0
• Additional information: †Before opening this issue, I did scan through closed issues and found other reports of similar behavior, however many of them are related to Azure, which this one does not seem to be.

[JimBobSquarePants]

See the comment in #1029

https://github.com/SixLabors/ImageSharp/issues/1029#issuecomment-544061230

The decoder is waiting for the end of the stream which remains open. You should be using your stream.

using var stream = await response.Content.ReadAsStreamAsync();

[QuantumToasted]

Hello, thank you for the response.
I noted in the comments that I omitted my using statements as I was pasting a simplified version of the code. Here is the actual code as it is used:

using var response = await Http.GetAsync(url);
if (response.StatusCode == HttpStatusCode.NotFound)
{
    return CommandErrorLocalized("emojiparser_notfound");
}

await using var stream = await response.Content.ReadAsStreamAsync();

using var image = Image.Load<Rgba32>(stream);

[JimBobSquarePants]

Ah right.... The HttpClient bit is a red herring. Looks like we're unable to decode that png, I suspect because of the presence of the unhandled bkGD chunk

I'll see if I can get a fix out asap.