[Bug] Silent Failures Due to Swallowed Errors in Critical Backend Paths

## 📌 Summary
Multiple critical execution paths in the DebateAI backend silently ignore errors returned from database operations and core services. These swallowed errors are neither logged nor propagated, leading to hidden failures, potential data loss, and significant difficulty debugging production issues.

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## 🧩 Affected Components
Silent failures have been observed in (but may not be limited to):

- Database operations (`backend/db/db.go`)
- Debate vs Bot controllers (`backend/controllers/debatevsbot_controller.go`)
- Matchmaking and room creation logic
- Profile and authentication-related database writes

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## 🔍 Problem Description
Several code paths contain patterns such as:

In these cases:

- Errors are completely ignored
- Execution continues as if the operation succeeded
- Failures remain invisible to developers and operators
- This is especially problematic for database writes, matchmaking logic, and debate outcome persistence.

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## ❌ Expected Behavior

- Errors occurring in critical paths should be:
- Logged with meaningful contextual information, and/or
- Returned or propagated to the caller for proper handling
- Silent failures should be avoided, particularly where data integrity or user-facing correctness is involved

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## ✅ Actual Behavior

- Errors are swallowed without logging or propagation
- Failures are silent and difficult to detect
- System state may become inconsistent without any indication

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## 💥 Impact

- Potential silent data loss (e.g., failed DB writes)
- Increased difficulty diagnosing production incidents
- educed observability and reliability
- Higher maintenance and debugging cost over time