Cancelling vscode warnning `Incorrect type. Expected "array"`

I'm writing a manifest.json as instructed in the google chrome extensions- getting started and the manifest is working fine, but on vscode I'm getting the following error :

As said, it's working just fine despite of this warning, but I want it gone. Is there a way to cancel this error? Or, of course, is there a way to correct my code so it will not show warnings?

Thanks