fundingmanager+lnwallet: ensure proposed channel reserve is above dust limit

lnwallet/errors.go

@@ -59,6 +59,15 @@ func ErrCsvDelayTooLarge(remoteDelay, maxDelay uint16) ReservationError {
 	}
 }
 
+// ErrChanReserveTooSmall returns an error indicating that the channel reserve
+// the remote is requiring is too small to be accepted.
+func ErrChanReserveTooSmall(reserve, dustLimit btcutil.Amount) ReservationError {
+	return ReservationError{
+		fmt.Errorf("channel reserve of %v sat is too small, min is %v "+
+			"sat", int64(reserve), int64(dustLimit)),
+	}
+}
+
 // ErrChanReserveTooLarge returns an error indicating that the chan reserve the
 // remote is requiring, is too large to be accepted.
 func ErrChanReserveTooLarge(reserve,