GraphQL Service Crashes When the Provided Map Key is not Present in the Map Type

[ThisaruGuruge]

Description:
Check the following code:

import ballerina/graphql;

service on new graphql:Listener(4000) {    
    resource function get person() returns Person {
        return {
            names: {
                one: "One",
                two: "Two"
            },
            id: 1
        };
    }
}

public type Person record {|
    map<string> names;
    int id;
|};

When the following document is sent to the GraphQL service, it crashes.

{
  person {
    names(key:"kja")
  }
}