diff --git a/packages/api/src/services/library_item.ts b/packages/api/src/services/library_item.ts
index 70c01c454..fae25fb11 100644
--- a/packages/api/src/services/library_item.ts
+++ b/packages/api/src/services/library_item.ts
@@ -540,7 +540,7 @@ export const buildQuery = (
       return `(${serialized})`
     }
 
-    throw new Error('Missing AST type.')
+    return null
   }
 
   return serialize(searchQuery)