-const advertiseDoNotTrack = (_, res, next) => {
- res.setHeader('Tk', 'N')
+import * as express from 'express'
+
+const advertiseDoNotTrack = (_, res: express.Response, next: express.NextFunction) => {
+ if (!res.headersSent) {
+ res.setHeader('Tk', 'N')
+ }
+
return next()
}