Handle assemblies gracefully

[mariam-abdulla]

This pull request improves the robustness of the TerminalTestReporter class by adding safe dictionary access for test progress state lookups. Instead of directly accessing the _assemblies dictionary, the code now uses TryGetValue to prevent potential exceptions when an execution ID is missing. This ensures smoother error handling and avoids crashes in edge cases.

Error handling and robustness improvements:

• Replaced direct dictionary access with TryGetValue in methods such as TestCompleted, TestDiscovered, and TestInProgress to gracefully handle missing execution IDs and prevent exceptions. [1] [2] [3]
• Updated AssemblyRunCompleted to handle cases where the execution ID does not exist by reporting non-zero exit codes to the terminal and skipping state updates, improving stability for non-"TestHost" scenarios.

[Copilot]

Pull request overview

This PR improves error handling in the TerminalTestReporter class by replacing direct dictionary access with TryGetValue calls to prevent KeyNotFoundException exceptions when an executionId is not found in the _assemblies dictionary.

Key changes:

• Replaced four instances of direct dictionary access (_assemblies[executionId]) with safe TryGetValue calls
• Added graceful handling for missing executionIds with early returns
• Special handling in AssemblyRunCompleted to still report non-zero exit codes even when the executionId is not found

[nohwnd]

Which issue are we fixing here? It feels like this change will ignore more unexpected errors. Is it possible to rather solve the pre-condition that makes this fail?