Fix variable placement for response size rendering

Author: Victowolf

packages/devtools_app/lib/src/screens/network/network_request_inspector_views.dart

@@ -625,6 +625,7 @@ class NetworkRequestOverviewView extends StatelessWidget {
   }
 
   List<Widget> _buildGeneralRows(BuildContext context) {
+    final bytes = data.responseBytes;
     return [
       // TODO(kenz): show preview for requests (png, response body, proto)
       _buildRow(
@@ -662,7 +663,7 @@ class NetworkRequestOverviewView extends StatelessWidget {
       _buildRow(
         context: context,
         title: 'Response Size',
-        child: _valueText(_formatBytes(data.responseBytes)),
+        child: _valueText(bytes != null ? _formatBytes(bytes) : '-'),
       ),
       const SizedBox(height: defaultSpacing),
 

packages/devtools_app/lib/src/screens/network/network_screen.dart

@@ -429,7 +429,8 @@ class ResponseSizeColumn extends ColumnData<NetworkRequest> {
 
   @override
   String getDisplayValue(NetworkRequest dataObject) {
-    return _formatBytes(dataObject.responseBytes);
+    final bytes = dataObject.responseBytes;
+    return bytes != null ? _formatBytes(bytes) : '-';
   }
 }