The bug that hid behind a swallowed error
My leaderboard page had been silently rendering empty in production. The query was failing the whole time — the database was missing a permission grant — but the code ignored the error object and treated 'failed' the same as 'no rows'. The fix that mattered wasn't the grant; it was making every page throw on query errors. The very next deploy failed loudly with 'permission denied' and pointed at the exact problem. Errors you swallow don't go away, they just stop telling you where they are.