fixed: enabled never be false

[limerickgds]

when playground is undefined , createPlaygroundOptions still set its default value

TODO:

• Update CHANGELOG.md with your change (include reference to issue & this PR)
• Make sure all of the significant new logic is covered by tests
• Rebase your changes on master so that they can be merged easily
• Make sure all tests and linter rules pass

[apollo-cla]

@limerickgds: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Meteor Contributor Agreement here: https://contribute.meteor.com/

[martijnwalraven]

@limerickgds Can you elaborate on what behavior this is expected to enable?

[limerickgds]

@martijnwalraven i wan't to provide terminal/console use apoolo-server-koa in a production environment. In this code, PlaygroundConfig has default value, enabled is true. so apolloServer. playgroundOptions is always not undefined.

https://github.com/apollographql/apollo-server/blob/master/packages/apollo-server-koa/src/ApolloServer.ts#L138

[abernix]

@limerickgds Are you able to investigate the test failures here?

[limerickgds]

@abernix done

[abernix]

I'm pretty sure the actual problem has been fixed in a number of other ways (see any number of Playground-related bug fixes: #1855, #1607, #1586, #1516, #1495), but this still makes the code more clear, and you certainly deserve commit credit for trying. Thanks!