Flutter app (FluffyChat) build error: .dart_tool/flutter_gen/pubspec.yaml missing .lock file

The recent build of FluffyChat failed with:

2024-09-04 02:07:10,798 ERROR: Found dependency file without lock at .dart_tool/flutter_gen/pubspec.yaml

The above error message seems to come from fdroidserver scanner, by a check recently introduced in 1d796b734f1cf6a820070348615d8f93b1eb2c10 by @linsui (which is why it didn't occur on earlier FluffyChat builds).

I'm neither an Android or Flutter developer, nor did I locally reproduce this, so the following is just some assumptions. Still, as far as I understood, .dart_tool/flutter_gen/pubspec.yaml is autogenerated by Flutter (see also the linked dart-lang/build#2835) if pubspec.yaml contains

flutter:
  generate: true

This is the case for FluffyChat.

Looking at the code from the above Flutter pull request (Ctrl+F emptyPubspecTemplate), this seems to create a basically empty pubspec.yaml (just with name: and description:) to make other tools happy which expect a pubspec.yaml to exist for each package. (flutter_gen apparently generates some (pseudo) package for easier use of e.g. assets.)

Not sure whether this should be fixed in metadata/chat.fluffy.fluffychat.yml (and probably others) or in fdroidserver.