[release/9.5] Fix GenAI visualizer when span is missing peer attribute

[JamesNK]

Customer Impact

A user reported an unhandled error in the dashboard when viewing some GenAI telemetry from Semantic Kernel. The problem is recorded telemetry doesn't have a peer attribute, which later causes an error when rendering the page.

The fix is to default the peer name to unknown-peer (exact name doesn't matter, as long as it has a name). It now always has a value and there is no chance of NRE.

Basically, before:

PeerName = OtlpHelpers.GetPeerAddress(viewModel.Span.Attributes)!; // <- bad null suppression

After:

PeerName = OtlpHelpers.GetPeerAddress(viewModel.Span.Attributes) ?? "unknown-peer";

Testing

Unit tests

Risk

Low

Regression?

No

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/dotnet/aspire/main/eng/scripts/get-aspire-cli-pr.sh | bash -s -- 11765

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/dotnet/aspire/main/eng/scripts/get-aspire-cli-pr.ps1) } 11765"

[Copilot]

Pull Request Overview

This PR fixes a bug in the GenAI visualizer dialog where spans missing peer attributes would cause null reference issues. The fix ensures that when no peer resource or peer address is available, a fallback "unknown-peer" name is used instead of null.

Key changes:

• Added proper fallback handling for missing peer attributes in the GenAI visualizer dialog
• Made PeerName and SourceName properties required (non-nullable) to prevent null reference exceptions
• Added comprehensive test coverage for the GenAI visualizer dialog scenarios

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
GenAIVisualizerDialogViewModel.cs	Fixed null handling for peer names by making properties required and adding fallback logic
GenAIVisualizerDialogTests.cs	Added new test file with comprehensive test coverage for GenAI visualizer scenarios
Program.cs	Added test endpoint for GenAI trace with display error scenario

[joperezr]

Low Risk, customer reported, fixing a new feature. Approved.