MapFailureStrategy may return null from SidMapper

src/main/java/no/ssb/dlp/pseudo/service/pseudo/PseudoField.java

@@ -149,7 +149,7 @@ private Optional<Object> mapOptional(String v, RecordMapProcessor<PseudoMetadata
             metadataProcessor.addMetric(FieldMetric.NULL_VALUE);
             return Optional.empty();
         } else {
-            return Optional.of(recordMapProcessor.process(Map.of(this.getName(), v)).get(this.getName()));
+            return Optional.ofNullable(recordMapProcessor.process(Map.of(this.getName(), v)).get(this.getName()));
         }
     }