Generic error with ofborg

I am working on a improvement on Flet on NixOS in a way that it comes pre-configured with the Flutter frontend [1].

The problem is that I am stuck with a Ofborg error [2] that I have no idea how to solve. It seems that it is complaining about missing hashes, but where? Where is the context? Where is the stacktrace? Why I can’t reproduce it locally? It’s not something like a bug switch that you force push or something to retrigger a build then it vanishes. It’s consistent.

Locally everything builds and happily works.

[1] https://github.com/NixOS/nixpkgs/pull/279936
[2] Output path comparison · GitHub