The latest articles on DEV Community by builtstack (@builtstack). https://dev.to/builtstack https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F4143380%2Fa983dbbc-5e9c-4745-b8f1-7e01181d6da3.png https://dev.to/builtstack en builtstack Fri, 25 Sep 2026 19:44:21 +0000 https://dev.to/builtstack/3-bugs-that-cost-me-3-weeks-building-a-form-builder-1mfb https://dev.to/builtstack/3-bugs-that-cost-me-3-weeks-building-a-form-builder-1mfb <p>I built a form builder (mini-Tally) as a side project.</p> <p>The code was the easy part. These three bugs cost me the most time.</p> <h2> Bug 1 — Typing didn't work </h2> <p>In my form editor, typing in a question field did nothing. The letters just didn't appear.</p> <p>Cause: I used <code>setBlocks(blocks.map(...))</code> — which captures stale state.</p> <p>Fix — use the functional form:</p> <div class="highlight js-code-highlight"> <pre class="highlight plaintext"><code> typescript setBlocks((prev) =&gt; prev.map((b) =&gt; b.id === id ? { ...b, label } : b )); Bug 2 — GitHub ate my src folder I dragged my project folder into GitHub's web uploader. It said "uploaded 20 files." The build failed with "module not found: src/main.tsx". The browser uploader had silently skipped the src folder entirely. Lesson: don't use the web uploader for folders with nested files. Use git. Bug 3 — Auth worked locally, broke in production Sign-up worked on localhost. On the deployed site, it did nothing. No error, just silence. Cause: Supabase redirect URLs were only configured for localhost. Supabase rejected requests from the production domain. Fix: After deploying, add your production URL to Supabase → Authentication → URL Configuration. Both the Site URL and the Redirect URLs list. The stack Next.js 16 (App Router, Server Actions) Supabase (Auth + Postgres + RLS) Tailwind CSS TypeScript What I built A form builder with 6 question types, public form pages, and CSV export. Live demo: https://getjustforms.vercel.app If you hit any of these bugs, ping me in the comments. </code></pre> </div> debugging react typescript builtstack Fri, 25 Sep 2026 18:13:55 +0000 https://dev.to/builtstack/how-i-built-a-form-builder-with-nextjs-16-and-supabase-1h1i https://dev.to/builtstack/how-i-built-a-form-builder-with-nextjs-16-and-supabase-1h1i <p>Three weeks ago I built a form builder. Not a company — just a tool I needed.</p> <p>Here are the three bugs that cost me the most time.</p> <h2> Bug #1 — React state closure </h2> <p>Typing in the question editor did nothing. The letters didn't appear.</p> <p>Cause: I was mapping over state directly instead of using the functional update form.</p> <div class="highlight js-code-highlight"> <pre class="highlight plaintext"><code> typescript // ❌ Broken setBlocks(blocks.map((b) =&gt; b.id === id ? { ...b, label } : b)); // ✅ Correct setBlocks((prev) =&gt; prev.map((b) =&gt; b.id === id ? { ...b, label } : b)); </code></pre> </div> webdev nextjs supabase showdev