here is the error? how to fix it i am using the latest node

 agent ??= new https.Agent({ ...this.client.options.http.agent, keepAlive: true });

 SyntaxError: Unexpected token '??='
 at wrapSafe (internal/modules/cjs/loader.js:1001:16)
 at Module._compile (internal/modules/cjs/loader.js:1049:27)
 at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10)
 at Module.load (internal/modules/cjs/loader.js:950:32)
 at Function.Module._load (internal/modules/cjs/loader.js:790:12)
 at Module.require (internal/modules/cjs/loader.js:974:19)
 at require (internal/modules/cjs/helpers.js:93:18)
 at Object.<anonymous> (/app/node_modules/discord.js/src/rest/RESTManager.js:5:20)
 at Module._compile (internal/modules/cjs/loader.js:1085:14)
 at Object.Module._extensions..js (internal/modules/cjs/loader.js:1114:10)