diff --git a/frontend/assets/patcherjs/modules/zip.js/z-worker.js b/frontend/assets/patcherjs/modules/zip.js/z-worker.js
index 16dce86c5..4f5c9ac31 100644
--- a/frontend/assets/patcherjs/modules/zip.js/z-worker.js
+++ b/frontend/assets/patcherjs/modules/zip.js/z-worker.js
@@ -36,6 +36,9 @@
     },
     f = {};
   function h(t) {
+    if (typeof c[t.codecClass] !== 'function') {
+      throw new Error("Invalid codecClass");
+    }
     var e = c[t.codecClass],
       r = t.sn;
     if (f[r]) throw Error("duplicated sn");