proxyReq.setHeader can not set headers after they are sent - node.js

Question

i am building a node.js proxy and i want to add a conditional header
proxy.on('proxyReq', (proxyReq, req, res) => {
const realIP = parseHttpHeader(req.headers['x-real-ip'])[0];
const path = parseHttpHeader(req.headers['x-original-uri'])[0];
pAny([
check_ip(realIP) ,
check_path(path) ,
check_geo(realIP)
]).then(result => {
console.log (result , "result " )
if (result) {
proxyReq.setHeader('namespace' , 'foo');
} else {
proxyReq.setHeader('namespace' , 'bar'); }
console.log('sending req ')
});
});
.
async function check_ip(realIP) {
try {
const result = await ipModel.findOne({ip: realIP}).exec()
console.log(realIP , result , "ip")
if (result) {
return true
} else {
return false
}
} catch (e) {
throw e;
}
}
and it works just fine till i use the methos check_ip then i get the error
(node:3793) UnhandledPromiseRejectionWarning: Error: Can't set headers after they are sent.
at validateHeader (_http_outgoing.js:491:11)
at ClientRequest.setHeader (_http_outgoing.js:498:3)
at /home/master/IPS/server.js:109:14
at <anonymous>
at process._tickCallback (internal/process/next_tick.js:189:7)
(node:3793) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:3793) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
as the error clearly states i am handeling a promise in the wrong way but i don't know how to fix it i tried using callbacks i tried using await

Answer 1

make the check_ip return a promise and try
function check_ip(realIP) {
return ipModel.findOne({ ip: realIP }).exec();
}