Log clear error if we fail to retrieve debug log upload key

js/modules/debuglogs.js

@@ -38,6 +38,9 @@ exports.upload = async content => {
       'user-agent': USER_AGENT,
     },
   });
+  if (!signedForm.body) {
+    throw new Error('Failed to retrieve token');
+  }
   const { fields, url } = signedForm.body;
 
   const form = new FormData();