🧹 Fix empty catch blocks in MainViewModel

[Avicennasis]

🎯 What: Replaced empty catch blocks with exception logging when cancelling CancellationTokenSource instances.
💡 Why: Empty catch blocks swallow exceptions, making it difficult to diagnose issues when things go wrong.
✅ Verification: Verified via dotnet build and dotnet test.
✨ Result: Improved maintainability and debugging capability by ensuring exceptions are properly logged instead of silently swallowed.

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PR created automatically by Jules for task 4846475184470251432 started by @Avicennasis

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