Prevent astNode is undefined for _entities & _service query

Author: hnq90

src/QueryComplexity.ts

@@ -190,6 +190,10 @@ export default class QueryComplexity {
               if (!field) {
                 break;
               }
+              // Prevent astNode's value is undefined when perform `_entities` & `_service` query
+              if (!field.astNode) {
+                (field.astNode as any) = {}
+              }
               const fieldType = getNamedType(field.type);
 
               // Get arguments