I Analyzed 500 AI Coding Mistakes and Built an...

Here's a pattern you've probably seen: const results = items.map(async (item) => { return await fetchItem(item); }); Looks fine, right? Your AI assistant wrote it. Tests pass. Code review approves it. Then production hits, and results is an array of Promises — not the values you expected. The await on line 2 does nothing. You needed Promise.all(items.map(...)) or a for...of loop. This isn't a TypeScript bug. It's a common LLM coding mistake — one of hundreds I found when I started researching AI