Polish camera settings layout and close media error responses

app.py

@@ -343,13 +343,14 @@ def media_json(path, playback=False):
         with urllib.request.urlopen(req, timeout=5) as r:
             return json.load(r)
     except urllib.error.HTTPError as exc:
-        if playback and path.startswith('/list?') and exc.code == 404:
-            try:
-                detail = json.loads(exc.read(4096))
-                if detail.get('error') == 'no recording segments found':
-                    return []
-            except (ValueError, AttributeError):
-                pass
+        with exc:
+            if playback and path.startswith('/list?') and exc.code == 404:
+                try:
+                    detail = json.loads(exc.read(4096))
+                    if detail.get('error') == 'no recording segments found':
+                        return []
+                except (ValueError, AttributeError):
+                    pass
         raise Problem('视频服务暂不可用，或该时段尚无可回放录像', 503)
     except Exception:
         raise Problem('视频服务暂不可用，或该时段尚无可回放录像', 503)