Custom function using supabase throws compilation error

I used the copilot feature to write a custom functions doing some basic calculations on a Supabase table.

I would like to query all posts of a user that that are no older than 30 days (from table posts in Supabase) and count the amount of posts for each beverage.

Inside the editor I receive two function code errors:

The await expression can only be used in an async function. Try marking the function body with either 'async' or 'async*'
'PostgrestFilterBuilder'. Try correcting the name to the name of an existing method, or defining a method named 'group'.

Any ideas how I can fix this or where I can look for a solution?

I appreciate any help - thank you so much in advance.

Here is my code:

import 'dart:convert';
import 'dart:math' as math;

import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';
import 'package:intl/intl.dart';
import 'package:timeago/timeago.dart' as timeago;
import '/flutter_flow/lat_lng.dart';
import '/flutter_flow/place.dart';
import '/flutter_flow/uploaded_file.dart';
import '/flutter_flow/custom_functions.dart';
import '/backend/backend.dart';
import 'package:cloud_firestore/cloud_firestore.dart';
import '/backend/schema/structs/index.dart';
import '/backend/supabase/supabase.dart';
import '/auth/supabase_auth/auth_util.dart';

List<dynamic> newCustomFunction(String user) {
  /// MODIFY CODE ONLY BELOW THIS LINE

  //   // query a supabase table posts where user_id matches the argument "user" and created_at ist not older that 30 days ago and do not user firebase. Then count all rows with the same beverage_name_de and return a list of json objects where beverage_name_de, beverage_name_en and count of rows with that name
  final thirtyDaysAgo = DateTime.now().subtract(Duration(days: 30));
  //final supabaseClient = SupabaseClient('url', 'key');
  final supabaseClient = SupaFlow.client;
  final response = await supabaseClient
      .from('posts')
      .select('beverage_name_de,beverage_name_en,count(*)')
      .eq('user_id', user)
      .gte('created_at', thirtyDaysAgo.toIso8601String())
      .group('beverage_name_de,beverage_name_en')
      .execute();
  final List<dynamic> result = response.data;
  return result;

  /// MODIFY CODE ONLY ABOVE THIS LINE
}