Firefox triggers Websocket error from IAsyncEnumerable Core MVC controller method

I am using a cancellable Javascript Fetch to retrieve a C# Microsoft.AspNet.WebApi.Core IAsyncEnumerable Controller method. There is no error with Chrome or Edge but Firefox logs the following: –

I don’t know if it is a W3C standard to convert a HTTP Fetch into a Websocket for Streaming or how Microsoft manages to embed it’s Browser-Link virus 🙁

This is plain .html not .cshtml or Razor pages.

Can anyone shed light on what’s happening?

Here’s the JS code: –

    <script type="application/javascript">

    async function doit()
    {
          const decoder = new TextDecoder();

          const abortControl = new AbortController();
          const signal = abortControl.signal;
          setTimeout(() =>
            {
                abortControl.abort();
                console.log("*ABORTED*")
            }, 2000); // Simulate a cancel after 2 secs

          const fetchOpts = {signal:signal, method:'GET', cache:"no-cache"};
          const response = await fetch("https://localhost:7196/data/yieldfamilyname?inname=made", fetchOpts);
          const reader = response.body.getReader();

          let result = await reader.read();

          while (!result.done && !signal.aborted)
          {
                var personText = decoder.decode(result.value).replace(/[|]/g, '').replace(/^,/, '');
                var person = JSON.parse(personText);
                console.log("chunk is", person.familyName);

                try {
                    result = await reader.read();
                }
                catch (err) {
                    console.log(err.message);
                    break;
                }
          }
          reader.releaseLock();
    }

    doit()
</script>

After the first Yield these messages are logged: –

chunk is MADE fred.html:32:14

Use of Mutation Events is deprecated. Use MutationObserver instead. browserLink:3299:5701

Tools extension connected browserLink:50:1248

Initializing tools services… browserLink:50:1248

Initializing tools design surface service browserLink:50:1248

Initializing tools selection service browserLink:50:1248

Initializing tools tag navigation service browserLink:50:1248

Initializing tools hotkey manager service browserLink:50:1248

Host extension connected browserLink:50:1248

Initializing host services… browserLink:50:1248

chunk is MADEBGWE fred.html:32:14

Firefox can’t establish a connection to the server at wss://localhost:44312/ChunkIt/.
aspnetcore-browser-refresh.js:234:24

WebSocket failed to connect. aspnetcore-browser-refresh.js:18:15

chunk is . . . .

ABORTED fred.html:19:14

The operation was aborted. fred.html:38:15