diff --git a/src/ts/plugins/embedworker.ts b/src/ts/plugins/embedworker.ts
index b2eef129..5f9a51d5 100644
--- a/src/ts/plugins/embedworker.ts
+++ b/src/ts/plugins/embedworker.ts
@@ -80,7 +80,8 @@ const whitelist = [
 
 const evaluation = globaly.eval
 
-const prop = Object.getOwnPropertyNames( globaly ).concat( Object.getOwnPropertyNames( this ))
+const propa = Object.getOwnPropertyNames( this ?? {} )
+const prop = Object.getOwnPropertyNames( globaly ).concat( propa)
 prop.push(
     //unsafe apis
     'open',