Fix: NanoBanana null-safe handling + bessere Fehlermeldungen

- _handle_nanobanana_generate: Prüfe code!=0 (z.B. 402=kein Guthaben), data=None-Safe
- _handle_nanobanana_status: data=None-Safe + response=None-Safe
- JavaScript: Bessere Fehlermeldung wenn resp.json() fehlschlägt
- Verhindert 'NoneType' object has no attribute 'get' Crash

article_server.py

@@ -493,7 +493,7 @@ def build_index(articles: list[dict]) -> str:
 <header>
   <div class="header-inner">
     <h1>Artikel-Übersicht</h1>
-    <p class="subtitle">{count} Artikel im Archiv · <a href="/?key={ACCESS_TOKEN}">Aktualisieren</a><span class="token-indicator">{token_status}</span></p>
+    <p class="subtitle">{count} Artikel im Archiv · <a href="/?key={ACCESS_TOKEN}">Aktualisieren</a> · <a href="/nanobanana?key={ACCESS_TOKEN}" style="font-weight:600">🎨 Bild-Generator</a><span class="token-indicator">{token_status}</span></p>
   </div>
 </header>
 <div class="container">
@@ -1038,11 +1038,22 @@ h1{color:#c0392b;}p{color:#888;}</style></head>
             return
         
         result = _nanobanana_generate(prompt, image_urls, aspect_ratio, resolution)
+        # Prüfe auf Transport-Fehler (Netzwerk/HTTP)
         if "error" in result:
             self._json_reply(500, {"ok": False, "error": result["error"]})
             return
-        
+        # Prüfe auf NanoBanana API-Fehler (code != 0, z.B. 402 = kein Guthaben)
-        task_id = result.get("data", {}).get("taskId", "")
+        api_code = result.get("code", 0)
+        if api_code != 0:
+            api_msg = result.get("msg", "Unbekannter API-Fehler")
+            self._json_reply(500, {"ok": False, "error": f"NanoBanana: {api_msg} (Code {api_code})"})
+            return
+        # Null-Safe: data kann None sein
+        data = result.get("data") or {}
+        task_id = data.get("taskId", "")
+        if not task_id:
+            self._json_reply(500, {"ok": False, "error": "Keine taskId in API-Antwort"})
+            return
         self._json_reply(200, {"ok": True, "taskId": task_id})
 
     def _handle_nanobanana_status(self):
@@ -1060,11 +1071,12 @@ h1{color:#c0392b;}p{color:#888;}</style></head>
             self._json_reply(500, {"ok": False, "error": result["error"]})
             return
         
-        data = result.get("data", {})
+        # Null-Safe: data kann None sein
+        data = result.get("data") or {}
         self._json_reply(200, {
             "ok": True,
             "successFlag": data.get("successFlag"),
-            "resultImageUrl": data.get("response", {}).get("resultImageUrl"),
+            "resultImageUrl": (data.get("response") or {}).get("resultImageUrl"),
             "completeTime": data.get("completeTime"),
         })
 
@@ -2064,10 +2076,17 @@ async function startGeneration() {{
             method: 'POST',
             body: formData
         }});
-        const data = await resp.json();
+        
+        let data;
+        try {{
+            data = await resp.json();
+        }} catch (e) {{
+            const text = await resp.text().catch(() => '');
+            throw new Error('Server-Antwort nicht lesbar (Status ' + resp.status + '): ' + text.substring(0, 200));
+        }}
         
         if (!data.ok) {{
-            throw new Error(data.error || 'Unbekannter Fehler');
+            throw new Error(data.error || 'Unbekannter Fehler (Status ' + resp.status + ')');
         }}
         
         document.getElementById('spinnerText').textContent = 'Warte auf Ergebnis…';