Inconsistent error handling in async operations

[callebtc]

Description:
Some coroutines and background tasks lack proper error handling, leading to silent failures that could confuse users.

Affected Areas:

• Coroutine operations in CashuWalletManager
• Background NFC operations in BalanceCheckActivity
• Network requests without proper error propagation

Issues:

1. Silent failures in wallet operations
2. User not informed when background operations fail
3. Inconsistent error reporting patterns

Fix Instructions:
Add comprehensive error handling to all async operations:

// For coroutines:
scope.launch {
    try {
        // async operation
    } catch (e: Exception) {
        Log.e(TAG, "Operation failed", e)
        // Show user-friendly error message
        showErrorToUser("Operation failed: ${e.localizedMessage}")
    }
}

// For background threads:
Thread {
    try {
        // background operation  
    } catch (e: Exception) {
        Log.e(TAG, "Background operation failed", e)
        runOnUiThread {
            // Update UI with error
        }
    }
}.start()

Priority: High - affects user experience