Sentry-javascript: Make internal Sentry flags non-enumerable

[kamilogorek]

See: https://github.com/getsentry/sentry-javascript/pull/1521#issuecomment-456727494

[kahlil]

Great to see a response this quickly! It would be amazing if this would land soon, because the problem @atk described in the comment linked above actually prevents us from integrating Sentry at the moment.

[kamilogorek]

Fixed in 4.5.4 – https://github.com/getsentry/sentry-javascript/releases/tag/4.5.4
Sorry for the inconvenience :)

[kahlil]

Awesome, thanks!