Mono WASM test failure with "MONO_WASM: Unhandled error: TypeError: Failed to fetch"

## Build Information
Build: https://dev.azure.com/dnceng-public/cbb18261-c48f-4abb-8651-8cdcb5474649/_build/results?buildId=1396034
Build error leg or test failing: WasmTestOnChrome-MONO-ST-System.Buffers.Tests.WorkItemExecution
Pull request: https://github.com/dotnet/runtime/pull/127336

## Error Message

Fill the error message using [step by step known issues guidance](https://github.com/dotnet/arcade/blob/main/Documentation/Projects/Build%20Analysis/KnownIssueJsonStepByStep.md).

```json
{
"ErrorMessage": "MONO_WASM: Unhandled error: TypeError: Failed to fetch",
"ErrorPattern": "",
"BuildRetry": false,
"ExcludeConsoleLog": false
}
```

### Known issue validation
**Build: :mag_right:** https://dev.azure.com/dnceng-public/public/_build/results?buildId=1396034
**Error message validated:** `[MONO_WASM: Unhandled error: TypeError: Failed to fetch`]
**Result validation:** :white_check_mark: Known issue matched with the provided build.
**Validation performed at:** 4/25/2026 12:25:00 PM UTC

### Report
#### Summary
|24-Hour Hit Count|7-Day Hit Count|1-Month Count|
|---|---|---|
|0|0|0|