diff --git a/src/browser/setupWorker/start/createResponseListener.ts b/src/browser/setupWorker/start/createResponseListener.ts
index 222635d27..02f0f3b6f 100644
--- a/src/browser/setupWorker/start/createResponseListener.ts
+++ b/src/browser/setupWorker/start/createResponseListener.ts
@@ -18,7 +18,12 @@ export function createResponseListener(context: SetupWorkerInternalContext) {
     // Get the Request instance reference stored in the
     // request listener.
     const { requestId } = responseJson
-    const request = context.requests.get(requestId)!
+    const request = context.requests.get(requestId)
+
+    if (!request) {
+      return
+    }
+
     context.requests.delete(requestId)
 
     /**