Constrain torch unavailable example icon

@@ -167,15 +167,13 @@ class ToggleFlashlightButton extends StatelessWidget {
               },
               },
             );
             );
           case TorchState.unavailable:
           case TorchState.unavailable:
-            return const SizedBox(
-              width: 48.0,
-              child: Center(
+            return const SizedBox.square(
+              dimension: 48.0,
               child: Icon(
               child: Icon(
                 Icons.no_flash,
                 Icons.no_flash,
                 size: 32.0,
                 size: 32.0,
                 color: Colors.grey,
                 color: Colors.grey,
               ),
               ),
-              ),
             );
             );
         }
         }
       },
       },