diff --git a/server/src/main/java/org/elasticsearch/index/engine/LuceneSyntheticSourceChangesSnapshot.java b/server/src/main/java/org/elasticsearch/index/engine/LuceneSyntheticSourceChangesSnapshot.java
index 2bc517745f7e2..55b648ccdd6e3 100644
--- a/server/src/main/java/org/elasticsearch/index/engine/LuceneSyntheticSourceChangesSnapshot.java
+++ b/server/src/main/java/org/elasticsearch/index/engine/LuceneSyntheticSourceChangesSnapshot.java
@@ -83,7 +83,8 @@ public LuceneSyntheticSourceChangesSnapshot(
         this.maxMemorySizeInBytes = maxMemorySizeInBytes;
         this.sourceLoader = mappingLookup.newSourceLoader(SourceFieldMetrics.NOOP);
         Set<String> storedFields = sourceLoader.requiredStoredFields();
-        this.storedFieldLoader = StoredFieldLoader.create(mappingLookup.isSourceSynthetic() == false, storedFields);
+        assert mappingLookup.isSourceSynthetic() : "synthetic source must be enabled for proper functionality.";
+        this.storedFieldLoader = StoredFieldLoader.create(false, storedFields);
         this.lastSeenSeqNo = fromSeqNo - 1;
     }
 
diff --git a/server/src/main/java/org/elasticsearch/index/engine/SearchBasedChangesSnapshot.java b/server/src/main/java/org/elasticsearch/index/engine/SearchBasedChangesSnapshot.java
index e95aea24910e0..191125c59705e 100644
--- a/server/src/main/java/org/elasticsearch/index/engine/SearchBasedChangesSnapshot.java
+++ b/server/src/main/java/org/elasticsearch/index/engine/SearchBasedChangesSnapshot.java
@@ -83,6 +83,13 @@ protected SearchBasedChangesSnapshot(
             throw new IllegalArgumentException("Search_batch_size must be positive [" + searchBatchSize + "]");
         }
 
+        final AtomicBoolean closed = new AtomicBoolean();
+        this.onClose = () -> {
+            if (closed.compareAndSet(false, true)) {
+                IOUtils.close(engineSearcher);
+            }
+        };
+
         this.indexVersionCreated = indexVersionCreated;
         this.fromSeqNo = fromSeqNo;
         this.toSeqNo = toSeqNo;
@@ -91,13 +98,6 @@ protected SearchBasedChangesSnapshot(
         this.indexSearcher = newIndexSearcher(engineSearcher);
         this.indexSearcher.setQueryCache(null);
 
-        final AtomicBoolean closed = new AtomicBoolean();
-        this.onClose = () -> {
-            if (closed.compareAndSet(false, true)) {
-                IOUtils.close(engineSearcher);
-            }
-        };
-
         long requestingSize = (toSeqNo - fromSeqNo == Long.MAX_VALUE) ? Long.MAX_VALUE : (toSeqNo - fromSeqNo + 1L);
         this.searchBatchSize = (int) Math.min(requestingSize, searchBatchSize);