refactor: ensure param-assigned max_age from client.defaultMaxAge is a string

Author: panva

lib/actions/authorization/assign_defaults.js

@@ -10,7 +10,7 @@ export default function assignDefaults(ctx, next) {
   }
 
   if (params.max_age === undefined && client.defaultMaxAge !== undefined) {
-    params.max_age = client.defaultMaxAge;
+    params.max_age = client.defaultMaxAge.toString();
   }
 
   return next();