When using express and Node.JS, we will sometimes get this error:
Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
at new NodeError (node:internal/errors:277:15)
at ServerResponse.setHeader (node:_http_outgoing:563:11)
at ServerResponse.header (/node_modules/express/lib/response.js:771:10)
at file:///link/to/file/app.js:309:13 {
code: 'ERR_HTTP_HEADERS_SENT'