fix type error in web builds (#61556)
diff --git a/packages/flutter/lib/src/foundation/_platform_web.dart b/packages/flutter/lib/src/foundation/_platform_web.dart
index 42c9052..02b579a 100644
--- a/packages/flutter/lib/src/foundation/_platform_web.dart
+++ b/packages/flutter/lib/src/foundation/_platform_web.dart
@@ -17,7 +17,7 @@
}
platform.TargetPlatform _browserPlatform() {
- final String navigatorPlatform = html.window.navigator.platform.toLowerCase();
+ final String navigatorPlatform = html.window.navigator.platform?.toLowerCase() ?? '';
if (navigatorPlatform.startsWith('mac')) {
return platform.TargetPlatform.macOS;
}