fixed scenario of throwing stateError

Author: zopagaduanjr

packages/path_provider/path_provider_android/lib/path_provider_android.dart

@@ -84,6 +84,9 @@ class PathProviderAndroid extends PathProviderPlatform {
   Future<String?> getDownloadsPath() async {
     final List<String>? paths =
         await getExternalStoragePaths(type: StorageDirectory.downloads);
-    return paths?.first;
+    if (paths != null && paths.isNotEmpty) {
+      return paths.first;
+    }
+    return null;
   }
 }

packages/path_provider/path_provider_android/test/path_provider_android_test.dart

@@ -93,5 +93,11 @@ void main() {
       final String? path = await pathProvider.getDownloadsPath();
       expect(path, kExternalStoragePaths);
     });
+
+    //TODO: override externalStoragePaths as empty
+    test('getDownloadsPath null', () async {
+      final String? path = await pathProvider.getDownloadsPath();
+      expect(path, null);
+    });
   });
 }