Fix Flutter & NestJS Bugs

My cross-platform Flutter app (clean architecture with bloc / cubit, get_it, and dio) is running into two critical issues: crashes and intermittent data-loading failures. The odd part is that I can’t pin the problems to any particular screen or user action; they seem to strike at random.

On the server side, the NestJS API (TypeScript) connects to MongoDB and uses Firebase services for a few features. I suspect some of the faults may originate there, so I want the whole stack inspected and stabilised rather than treating the mobile code in isolation.

What I need from you:
• Trace and eliminate the crash causes in the Flutter client.
• Ensure data consistently loads through the dio layer, updating bloc/cubit states correctly.
• Audit the NestJS endpoints, MongoDB queries, and Firebase interactions to make sure nothing is returning malformed or unexpected data that could be breaking the app.

Once you’re done, the app should run without random terminations, and all screens must show fresh data every time. I’ll provide the full repository and steps to reproduce the current behaviour; you deliver clean commits, concise notes on what was fixed, and a short hand-off call or document so I can follow the changes.