Gestisce errori email del form contatti senza 500 opaco. (#18)

Invia via fetch/JSON, cattura fallimenti Cloudflare Email (con retry senza Reply-To) e reindirizza a #contatti.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/scripts/nx-contact-form.ts

@@ -1,4 +1,4 @@
-/** Modulo contatti in pagina (#contatti): mailto o POST Formspree. */
+/** Modulo contatti in pagina (#contatti): mailto o POST /api/contact. */
 interface ContactFormCfg {
   actionUrl: string;
   mailto: string;
@@ -52,11 +52,18 @@ function readCfg(): ContactFormCfg {
   return JSON.parse(raw) as ContactFormCfg;
 }
 
+function showError(message: string): void {
+  const err = document.getElementById('nx-contact-form-error');
+  if (!err) return;
+  err.textContent = message;
+  err.classList.remove('hidden');
+}
+
 function bind(): void {
   const form = document.getElementById('nx-contact-form') as HTMLFormElement | null;
   if (!form) return;
 
-  form.addEventListener('submit', (e) => {
+  form.addEventListener('submit', async (e) => {
     const cfg = readCfg();
     const err = document.getElementById('nx-contact-form-error');
     if (err) err.classList.add('hidden');
@@ -69,17 +76,44 @@ function bind(): void {
       )?.value;
       if (!token) {
         e.preventDefault();
-        if (err) {
-          err.textContent = cfg.turnstileError;
-          err.classList.remove('hidden');
-        }
+        showError(cfg.turnstileError);
         return;
       }
     }
 
     if (cfg.actionUrl) {
+      e.preventDefault();
+      const submitBtn = form.querySelector<HTMLButtonElement>('button[type="submit"]');
+      if (submitBtn) submitBtn.disabled = true;
+      try {
+        const res = await fetch(cfg.actionUrl, {
+          method: 'POST',
+          headers: { Accept: 'application/json' },
+          body: new FormData(form),
+        });
+        const data = (await res.json().catch(() => null)) as
+          | { ok?: boolean; error?: string; redirect?: string }
+          | null;
+        if (!res.ok) {
+          showError(
+            (data && typeof data.error === 'string' && data.error) ||
+              'Invio non riuscito. Riprova tra poco.',
+          );
+          return;
+        }
+        const target =
+          (data && typeof data.redirect === 'string' && data.redirect) ||
+          cfg.successRedirect ||
+          `${window.location.pathname}${window.location.search}#contatti`;
+        window.location.assign(target);
+      } catch {
+        showError('Errore di rete. Controlla la connessione e riprova.');
+      } finally {
+        if (submitBtn) submitBtn.disabled = false;
+      }
       return;
     }
+
     e.preventDefault();
     const fd = new FormData(form);
     const name = String(fd.get(cfg.fieldName) ?? '').trim();
@@ -101,10 +135,7 @@ function bind(): void {
       window.location.href = `mailto:${cfg.mailto}?subject=${subject}&body=${body}`;
       return;
     }
-    if (err) {
-      err.textContent = cfg.configError;
-      err.classList.remove('hidden');
-    }
+    showError(cfg.configError);
   });
 }