Вытащил солюшен на уровень выше, чтобы прощё было дотнетить

ApplicationLayer/GeneralExceptions/AlreadyExistsException.cs

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+namespace ApplicationLayer.GeneralExceptions;
+
+public class AlreadyExistsException(string message) : ApiException(message);

ApplicationLayer/GeneralExceptions/ApiException.cs

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+namespace ApplicationLayer.GeneralExceptions;
+
+public class ApiException(string message) : Exception(message);

ApplicationLayer/GeneralExceptions/EntityNotFoundByIdException.cs

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+using Domains;
+
+namespace ApplicationLayer.GeneralExceptions;
+
+/// Exception to throw when entity not found
+/// <param name="id">Identifier of entity</param>
+/// <typeparam name="T">Type of entity</typeparam>
+public class EntityNotFoundByIdException<T>(Guid id) : EntityNotFoundException($"{typeof(T).Name} with id {id} not found.")
+    where T : class, IEntity;

ApplicationLayer/GeneralExceptions/EntityNotFoundException.cs

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+namespace ApplicationLayer.GeneralExceptions;
+
+/// Exception to throw when entity not found
+public class EntityNotFoundException(string message) : ApiException(message);