Access denied error when running demo app for the first time

[kat-liger]

I am trying to run the GraphQLDemoApp for the first time, so I downloaded the repo and run the command:

php bin/console server:start

I am getting the correct (error) response to 'http://127.0.0.1:8000/graphql' but when I am trying to specify query, this is what I get:

| => curl -XPOST 'http://127.0.0.1:8000/graphql' -F 'query={ todos { id } }'
{
    "errors": [
        {
            "message": "An exception occured in driver: SQLSTATE[HY000] [1045] Access denied for user \u0027root\u0027@\u0027localhost\u0027 (using password: YES)"
        }
    ]
}

What am I missing here?