Add error type

core/src/errors.rs

@@ -136,6 +136,9 @@ pub enum BridgeError {
     /// OperatorFundingUtxoAmountNotEnough is returned when the operator funding utxo amount is not enough
     #[error("OperatorFundingUtxoAmountNotEnough: Operator funding utxo amount is not enough, pls send some amount here: {0}, then call the set_operator_funding_utxo RPC")]
     OperatorFundingUtxoAmountNotEnough(bitcoin::Address),
+    /// OperatorWithdrawalFeeNotSet is returned when the operator withdrawal fee is not set
+    #[error("OperatorWithdrawalFeeNotSet")]
+    OperatorWithdrawalFeeNotSet,
     /// InvalidKickoffUtxo is returned when the kickoff utxo is invalid
     #[error("InvalidKickoffUtxo")]
     InvalidKickoffUtxo,

core/src/operator.rs

@@ -306,8 +306,19 @@ where
     }
 
     async fn is_profitable(&self, withdrawal_amount: u64) -> Result<bool, BridgeError> {
-        let net_profit = self.config.bridge_amount_sats - withdrawal_amount;
-        Ok(self.config.operator_withdrawal_fee_sats.unwrap() < net_profit)
+        // Check if the withdrawal amount is within the acceptable range
+        if withdrawal_amount > self.config.bridge_amount_sats {
+            Ok(false)
+        } else {
+            // Calculate net profit after the withdrawal
+            let net_profit = self.config.bridge_amount_sats - withdrawal_amount;
+
+            // Check if the operator withdrawal fee is set and calculate profitability
+            match self.config.operator_withdrawal_fee_sats {
+                Some(fee) => Ok(fee < net_profit),
+                None => Err(BridgeError::OperatorWithdrawalFeeNotSet),
+            }
+        }
     }
 
     async fn new_withdrawal_sig(