◇ Could this help me?
Yes. All three are real gaps and the ordering is right: unhandled failure states, shared dev and production data, and missing audit logs are exactly what turns a working app into an incident. The audit trail point deserves the most attention because it is the only one of the three that cannot be added retroactively for events that already happened. This is a general practice.
Audit this project for three specific gaps and report each before changing anything. First, error handling: find every path where a failure would reach the user as a blank screen, a stack trace, or a bare 500, and propose graceful states with a clear next action. Second, environment separation: tell me whether development and production share a database, API keys, or configuration, and what it would take to split them. Third, audit logging: list the sensitive actions such as plan changes, email changes, deletions, and permission changes, and show me where an immutable log entry would be written for each.