dynamite,nextcloud: Fix failing on empty body

packages/dynamite/lib/src/openapi_builder.dart

@@ -58,9 +58,14 @@ class OpenAPIBuilder implements Builder {
                   ..returns = refer('Future<Uint8List>')
                   ..type = MethodType.getter
                   ..modifier = MethodModifier.async
-                  ..lambda = true
                   ..body = const Code(
-                    'Uint8List.fromList((await toList()).reduce((final value, final element) => [...value, ...element]))',
+                    '''
+                  final chunks = await toList();
+                  if (chunks.isEmpty) {
+                    return Uint8List(0);
+                  }
+                  return Uint8List.fromList(chunks.reduce((final value, final element) => [...value, ...element]));
+                    ''',
                   ),
               ),
               Method(

packages/nextcloud/lib/src/nextcloud.openapi.dart

@@ -10,8 +10,14 @@ export 'package:cookie_jar/cookie_jar.dart';
 part 'nextcloud.openapi.g.dart';
 
 extension HttpClientResponseBody on HttpClientResponse {
-  Future<Uint8List> get bodyBytes async =>
-      Uint8List.fromList((await toList()).reduce((final value, final element) => [...value, ...element]));
+  Future<Uint8List> get bodyBytes async {
+    final chunks = await toList();
+    if (chunks.isEmpty) {
+      return Uint8List(0);
+    }
+    return Uint8List.fromList(chunks.reduce((final value, final element) => [...value, ...element]));
+  }
+
   Future<String> get body async => utf8.decode(await bodyBytes);
 }