diff --git a/src/lib/functions/server.ts b/src/lib/functions/server.ts
index f7d56b9c698..05aefd9e9ff 100644
--- a/src/lib/functions/server.ts
+++ b/src/lib/functions/server.ts
@@ -206,7 +206,7 @@ export const createHandler = function (options) {
       const { error, result } = await func.invoke(event, clientContext)
 
       // check for existence of metadata if this is a builder function
-      if (/^\/.netlify\/(builders)/.test(request.path) && (!result.metadata || !result.metadata.builder_function)) {
+      if (/^\/.netlify\/(builders)/.test(request.path) && !result?.metadata?.builder_function) {
         response.status(400).send({
           message:
             'Function is not an on-demand builder. See https://ntl.fyi/create-builder for how to convert a function to a builder.',