카페에서 nodejs 공부하고 몽고디비를 연결하여 테스트해보려던 중 아래 에러가 발생했다. (node:2484) UnhandledPromiseRejectionWarning: ReferenceError: err is not defined at C:\Users\User\Desktop\web_workspace\boiler_plate\index.js:22:17 at processTicksAndRejections (internal/process/task_queues.js:93:5) (Use `node --trace-warnings ...` to show where the warning was created) originated either by throwing inside of an async function w..
