fix(core): drain buffers in flush() when there is no transport - #20207

fix(core): drain buffers in flush() when there is no transport#20207

nicohrubec merged 4 commits into

getsentry:developgetsentry/sentry-javascript:developfrom

sbs44:fix/flush-buffers-without-transportsbs44/sentry-javascript:fix/flush-buffers-without-transportCopy head branch name to clipboard