I have two requests
1.
'{"from":{"company":"Test Supplies","address1":"Test street ","city":"Test city","state":"ON","country":"CA","zip":"XXXXXX"},"to":{"company":null,"address1":"1437 C\u00f4te Joyeuse","city":"St Apollinaire","state":"QC","country":"CA","zip":"XXXXX"},"currency":"CAD","unit":"METRIC","expectedShipDate":"XXXXXX","packageType":"PACKAGE","storeIdentifier":"example.info","packages":[{"shopifyProductId":8591,"shopifyVariantId":0,"weight":0,"quantity":1},{"shopifyProductId":8561,"shopifyVariantId":0,"weight":0,"quantity":49}]}'

2.
'{"from":{"company":"Test Supplies","address1":"Test street ","city":"Test city","state":"ON","country":"CA","zip":"XXXXXX"},"to":{"company":null,"address1":"1437 C\u00f4te Joyeuse","city":"St Apollinaire","state":"QC","country":"CA","zip":"XXXXX"},"currency":"CAD","unit":"METRIC","expectedShipDate":"XXXXXX","packageType":"PACKAGE","storeIdentifier":"example.info","packages":[{"shopifyProductId":8591,"shopifyVariantId":0,"weight":0,"quantity":1},{"shopifyProductId":8561,"shopifyVariantId":0,"weight":0,"quantity":50}]}'

the only difference between them is the quantity of the product.

At the first request it returns rates, but at the second nothing

1. 

array (
'response' =>
(object) array(
'data' =>
(object) array(
'rates' =>
array (
0 =>
(object) array(
'serviceName' => 'Standard',
'carrierName' => 'UPS',
'serviceCode' => '604',
'totalCharge' => 85.43,
'estTransitDays' => '2',
'description' => 'Rate details',
'currency' => 'CAD',
),
1 =>
(object) array(
'serviceName' => 'Ground',
'carrierName' => 'Canpar',
'serviceCode' => '4500',
'totalCharge' => 184.31,
'estTransitDays' => '1',
'description' => 'Rate details',
'currency' => 'CAD',
),
2 =>
(object) array(
'serviceName' => 'Expedited',
'carrierName' => 'UPS',
'serviceCode' => '601',
'totalCharge' => 1018.01,
'estTransitDays' => '2',
'description' => 'Rate details',
'currency' => 'CAD',
),
3 =>
(object) array(
'serviceName' => 'UPS Saver',
'carrierName' => 'UPS',
'serviceCode' => '607',
'totalCharge' => 1203.01,
'estTransitDays' => '2',
'description' => 'Rate details',
'currency' => 'CAD',
),
4 =>
(object) array(
'serviceName' => 'Express',
'carrierName' => 'UPS',
'serviceCode' => '600',
'totalCharge' => 1585.15,
'estTransitDays' => '2',
'description' => 'Rate details',
'currency' => 'CAD',
),
),
),
'message' => 'Rates fetched successfully',
'success' => true,
),
'httpResponseCode' => 200,
)

2.

array (
  'response' => 
  (object) array(
     'data' => 
    (object) array(
       'rates' => 
      array (
      ),
    ),
     'message' => 'Rates fetched successfully',
     'success' => true,
  ),
  'httpResponseCode' => 200,
)

what could be the matter?

Fatal error: Uncaught Error: Class "woocommerce_eshipper_db" not found in /wp-content/plugins/eshipper-commerce/framework/plugin.php:240

Stack trace:

#0 /wp-includes/class-wp-hook.php(308): eshipper_plugin->eshipper_upgrades()

#1 /wp-includes/class-wp-hook.php(332): WP_Hook->apply_filters()

#2 /wp-includes/plugin.php(517): WP_Hook->do_action()

#3 /wp-settings.php(486): do_action()

#4 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1349): require('...')

#5 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Runner.php(1267): WP_CLI\Runner->load_wordpress()

#6 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/WP_CLI/Bootstrap/LaunchRunner.php(28): WP_CLI\Runner->start()

#7 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/bootstrap.php(83): WP_CLI\Bootstrap\LaunchRunner->process()

#8 phar:///usr/local/bin/wp/vendor/wp-cli/wp-cli/php/wp-cli.php(32): WP_CLI\bootstrap()

#9 phar:///usr/local/bin/wp/php/boot-phar.php(20): include('...')

#10 /usr/local/bin/wp(4): include('...')

#11 {main}

? thrown in /wp-content/plugins/eshipper-commerce/framework/plugin.php on line 240