3:00 부분부터 오류가 생기는데 어떻게 해결해야 할까요?

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PS C:\Users\User\git\backfront\backend> npm run dev

> backend@0.0.0 dev

> nodemon ./bin/www

[nodemon] 2.0.15

[nodemon] to restart at any time, enter `rs`

[nodemon] watching path(s): *.*

[nodemon] watching extensions: js,mjs,json

[nodemon] starting `node ./bin/www`

Not all input has been taken into account at your final specification.

Here's the report: 

 YAMLSemanticError: Map keys must be unique; "description" is repeated at line 1, column 1:

/api/hello:

^^^^^^^^^^^…