diff --git a/projects/common/util/unit-definition-sanitizer.ts b/projects/common/util/unit-definition-sanitizer.ts
index 69fd4509830654f6840bc82fa6bc722265ba7dcb..3ecca1217da3ecd205996e6809e26d5d7eb78c69 100644
--- a/projects/common/util/unit-definition-sanitizer.ts
+++ b/projects/common/util/unit-definition-sanitizer.ts
@@ -251,7 +251,7 @@ export abstract class UnitDefinitionSanitizer {
         content: doc.content
           .map((paragraph: ClozeDocumentParagraph) => ({
             ...paragraph,
-            content: paragraph.content
+            content: paragraph.content ? paragraph.content
               .map((paraPart: ClozeDocumentParagraphPart) => (
                 ['TextField', 'DropList', 'ToggleButton'].includes(paraPart.type) ?
                   {
@@ -264,7 +264,7 @@ export abstract class UnitDefinitionSanitizer {
                   {
                     ...paraPart
                   }
-              ))
+              )) : undefined
           }))
       } as ClozeDocument
     } as ClozeElement;