Index: Ringtoets/Integration/src/Ringtoets.Integration.Plugin/Merge/AssessmentSectionMergeHandler.cs
===================================================================
diff -u -rac2ef64a966ba1988c30df9773b383716e133eef -r0a3fd57580aff0d6487e195c67f315f628b1ced4
--- Ringtoets/Integration/src/Ringtoets.Integration.Plugin/Merge/AssessmentSectionMergeHandler.cs	(.../AssessmentSectionMergeHandler.cs)	(revision ac2ef64a966ba1988c30df9773b383716e133eef)
+++ Ringtoets/Integration/src/Ringtoets.Integration.Plugin/Merge/AssessmentSectionMergeHandler.cs	(.../AssessmentSectionMergeHandler.cs)	(revision 0a3fd57580aff0d6487e195c67f315f628b1ced4)
@@ -54,6 +54,27 @@
         public void PerformMerge(AssessmentSection targetAssessmentSection, AssessmentSection sourceAssessmentSection,
                                  IEnumerable<IFailureMechanism> failureMechanismsToMerge)
         {
+            if (targetAssessmentSection == null)
+            {
+                throw new ArgumentNullException(nameof(targetAssessmentSection));
+            }
+
+            if (sourceAssessmentSection == null)
+            {
+                throw new ArgumentNullException(nameof(sourceAssessmentSection));
+            }
+
+            if (failureMechanismsToMerge == null)
+            {
+                throw new ArgumentNullException(nameof(failureMechanismsToMerge));
+            }
+
+            BeforeMerge(targetAssessmentSection);
         }
+
+        private void BeforeMerge(AssessmentSection assessmentSection)
+        {
+            viewCommands.RemoveAllViewsForItem(assessmentSection);
+        }
     }
 }
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