Import null safe file picker

lib/widgets/toolbar.dart

@@ -574,9 +574,9 @@ class _ImageButtonState extends State<ImageButton> {
         fsType: FilesystemType.file,
         fileTileSelectMode: FileTileSelectMode.wholeTile,
       );
-      if (filePath.isEmpty) return '';
+      if (filePath != null && filePath.isEmpty) return '';
 
-      final File file = File(filePath);
+      final File file = File(filePath!);
       String url = await widget.onImagePickCallback!(file);
       print('Image uploaded and its url is $url');
       return url;

pubspec.lock

@@ -91,7 +91,7 @@ packages:
       name: filesystem_picker
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
+    version: "2.0.0-nullsafety.0"
   flutter:
     dependency: "direct main"
     description: flutter

pubspec.yaml

@@ -14,7 +14,7 @@ dependencies:
     sdk: flutter
   collection: ^1.15.0
   file_picker: ^3.0.0
-  filesystem_picker: ^1.0.4
+  filesystem_picker: ^2.0.0-nullsafety.0
   flutter_colorpicker: ^0.4.0-nullsafety.0
   flutter_keyboard_visibility: ^5.0.0
   image_picker: ^0.7.3