add exceptions

TheCyclopsProject/TheCyclopsContracts/Exceptions/ElementExistsException.cs

@@ -0,0 +1,14 @@
+namespace TheCyclopsContracts.Exceptions;
+
+public class ElementExistsException : Exception
+{
+    public string ParamName { get; private set; }
+
+    public string ParamValue { get; private set; }
+
+    public ElementExistsException(string paramName, string paramValue) : base($"There is already an element with value {paramValue} of parameter {paramName}")
+    {
+        ParamName = paramName;
+        ParamValue = paramValue;
+    }
+}

TheCyclopsProject/TheCyclopsContracts/Exceptions/ElementNotFoundException.cs

@@ -0,0 +1,11 @@
+namespace TheCyclopsContracts.Exceptions;
+
+public class ElementNotFoundException : Exception
+{
+    public string Value { get; private set; }
+
+    public ElementNotFoundException(string value) : base($"Element not found at value = {value}")
+    {
+        Value = value;
+    }
+}

TheCyclopsProject/TheCyclopsContracts/Exceptions/IncorrectDatesException.cs

@@ -0,0 +1,8 @@
+namespace TheCyclopsContracts.Exceptions;
+
+public class IncorrectDatesException : Exception
+{
+    public IncorrectDatesException(DateTime start, DateTime end) :
+        base($"The end date must be later than the start date. StartDate: {start:dd.MM.YYYY}. EndDate: {end:dd.MM.YYYY}")
+    { }
+}

TheCyclopsProject/TheCyclopsContracts/Exceptions/NullListException.cs

@@ -0,0 +1,6 @@
+namespace TheCyclopsContracts.Exceptions;
+
+public class NullListException : Exception
+{
+    public NullListException() : base("The returned list is null") { }
+}

TheCyclopsProject/TheCyclopsContracts/Exceptions/StorageException.cs

@@ -0,0 +1,6 @@
+namespace TheCyclopsContracts.Exceptions;
+
+public class StorageException : Exception
+{
+    public StorageException(Exception ex) : base($"Error while working in storage: {ex.Message}", ex) { }
+}