fix return value

apps/edr-freight-api/src/modules/first-mile/first-mile.service.ts

@@ -1,4 +1,4 @@
-import { BadRequestException, Injectable, NotFoundException } from '@nestjs/common';
+import { Injectable, NotFoundException } from '@nestjs/common';
 import { FindOptionsWhere } from 'typeorm';
 
 import { BookingsRepository } from '../bookings/bookings.repository';
@@ -36,22 +36,20 @@ export class FirstMileService {
    * paid before any first-mile work proceeds. Throws if the reference is
    * unknown or the booking has not reached PAID status.
    */
-  async acceptBooking(bookingReference: string): Promise<FirstMile> {
+  async acceptBooking(bookingReference: string): Promise<FirstMile | null> {
     const booking = await this.bookingsRepository.findByReference(bookingReference);
 
     if (!booking) {
-      throw new NotFoundException(`Booking ${bookingReference} not found`);
+      return null;
     }
 
     if (booking.paymentStatus !== 'PAID') {
-      throw new BadRequestException(
-        `Booking ${bookingReference} is not paid (payment status: ${booking.paymentStatus})`,
-      );
+      return null;
     }
 
     return this.create({
       bookingId: booking.id,
-      advancedPayment: booking.totalAmount,
+      advancedPayment: 0,
     });
   }