HttpClient abort issues in WASM when streaming

[radderz]

Description

When doing any form of streaming calls using HttpClient in Blazor WASM, an unhandled exception is shown (red bar by default at the bottom of screen) when there is a connection issue during streaming. I originally posted it in the aspnetcore repo but its a runtime issue.

dotnet/aspnetcore#55982

This can be triggered by a long running IAsyncEnumerable API or GRPC-Web Streaming call, I left a small repo project in the aspnetcore repo bug.

Reproduction Steps

The steps are a reasonably simple but the blazor UI needs to be connected to an api with the ability to remove connectivity (i.e. pulling out the network cable or disconnect wifi or kill the server). So the api needs to be on a different machine or be isolatable from the browser running the blazor wasm UI. Possibly devtunnels would make this easy to reproduce.

1. Run an API with an IAsyncEnumerable endpoint that runs forever
2. Run client connected to this endpoint on a different host
3. Disconnect/break the network connection between the browser and the api to trigger a network error

Expected behavior

The error is bubbled up to the calling C# code that is calling the streaming.

Actual behavior

Raises an unhandled exception that the caller cannot gracefully handle and reconnect.

Regression?

No response

Known Workarounds

None

Configuration

No response

Other information

No response

[radderz]

It looks to me that

function handle_abort_error (promise:Promise<any>) {
    promise.catch((err) => {
        if (err && err !== "AbortError" && err.name !== "AbortError" ) {
            Module.err("Unexpected error: " + err);
        }
        // otherwise, it's expected
    });
}

Should be changed to

function handle_abort_error (promise:Promise<any>) {
    promise.catch((err) => {
        if (!err) 
               return;        
        if (err === "AbortError" || err.name === "AbortError") 
                return; // normal abort
        if (err === "TypeError: network error" || (err.name === "TypeError" && err.message === "network error")) 
                return; // stream connection failure, should be handled by application

       Module.err("Unexpected error: " + err);
    });
}

Seems like a simple change.

[radderz]

https://github.com/radderz/BlazorAppJsonStreamBug

You can run the asp.net core project, which is hosting the web assembly page, once you are on the page and the timer is updating, kill the asp.net core api projects process (don't gracefully shut it down, do a kill) and you'll see the unhandled network error.

[maraf]

cc @pavelsavara

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