Try a challenge

You are the last reviewer before merge. The pull request below was written quickly, with help, and it has problems. Find them.

• Click the + on any line to flag it. Say what is wrong, pick a category, and rate it: blocker, major, minor or nit.
• Shift-click a second line to flag a range. Comments on the whole PR go in the summary when you finish.
• Nits are free but do not score. Flagging correct code costs precision, so only flag what you would actually raise.
• The timer is real. When it runs out, submit what you have.
• When you finish you see every planted defect, your hits and misses, and how your review compared with everyone else's.