Index: Ringtoets/Common/src/Ringtoets.Common.IO/Writers/CalculationConfigurationWriter.cs
===================================================================
diff -u -r020439f88aaed9dd51967acbc8518f37c95791d1 -rae137e9d1b26f1b37e47f2b4a6bf9ae03c6c9b2e
--- Ringtoets/Common/src/Ringtoets.Common.IO/Writers/CalculationConfigurationWriter.cs	(.../CalculationConfigurationWriter.cs)	(revision 020439f88aaed9dd51967acbc8518f37c95791d1)
+++ Ringtoets/Common/src/Ringtoets.Common.IO/Writers/CalculationConfigurationWriter.cs	(.../CalculationConfigurationWriter.cs)	(revision ae137e9d1b26f1b37e47f2b4a6bf9ae03c6c9b2e)
@@ -153,6 +153,8 @@
                 {
                     WriteCalculation(calculation, writer);
                 }
+
+                throw new ArgumentException($"Cannot write calculation of type '{child.GetType()}' using this writer.");
             }
         }