diff --git a/index.js b/index.js
index ead6e607e8bd14e0053269a8a330bd1cf67a5897..b6b304343e0e6427531e2068e50eb45e4fb91109 100644
--- a/index.js
+++ b/index.js
@@ -692,8 +692,8 @@ function extractGeneric(element) {
 function getConstraint(node, rawParam) {
     if (!node.constraint) {
         return "unknown";
-    }
-    let index = rawParam.indexOf(node.name.name) + node.name.name.length;
+    } 
+    let index = rawParam.indexOf(node.name.name) + (node.name.name?.length ?? node.name.length);
     let startIndex = null;
     while (index < rawParam.length) {
         if (startIndex == null) {