Update SemanticChatMemoryItem.cs

[Ahmed-Adel3]

Motivation and Context

1. Why is this change required? Possible Null reference exception.
2. What problem does it solve? Fix null reference in ToFormattedString function
3. What scenario does it contribute to? If ( Item ) object label and Details are null.

Description

In the SemanticChatMemoryItem.ToFormattedString function, ensure that the Details property is not null before trimming it. This change prevents potential NullReferenceExceptions when the Details property is null.

This modification ensures the stability of the ToFormattedString function when used in other parts of the code.

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines and the pre-submission formatting script raises no violations
• All unit tests pass, and I have added new tests where possible
• I didn't break anyone 😄

[crickman]

Nice clean change, thank you!

Just to confirm, you experienced null-ref exception on this line? (Just double-checking because of the nullable project settings and type declaration - not nullable.)

In the meantime, I'm just curious to see where else Details is referenced.

[Ahmed-Adel3]

Nice clean change, thank you!

Just to confirm, you experienced null-ref exception on this line? (Just double-checking because of the nullable project settings and type declaration - not nullable.)

In the meantime, I'm just curious to see where else Details is referenced.

Thanks @crickman for your reply,

Yes, I experienced the Null reference exception in this line, happened twice while I was running the Chat Copilot locally, but unfortunately didn't catch the scenario.

I'll try to reproduce it and if so, I may open an issue if it's caused by a bug.

I can see that Details is only referenced in the SemanticChatMemoryItem in the class constructor and the ToFormattedString function.

[crickman]

Wonderful, thanks for the quick reply. The nullable stuff isn't air-tight so I'm not surprised...probably serialization related (components outside of the project scope aren't bound to nullability hints - e.g. jsonserializer)