HandshakeException: Connection terminated during handshake - flutter

Question

I'm developing my first Flutter mobile app, and I'm facing an error trying to fetch data from API REST.
I set 2 get request using HTTP packages:
-the first is a single request, and it's fetching 'work orders' with attributes immediately available;
-the second one is another get request that fires per every 'work order' retrieved from the first request that take others attributes.
Basically, I run the first get request and I made a for loop to fire the second get request for all data.
So, the first request is working fine, instead the second one is giving me the following error for every time it fires:
[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled
Exception: HandshakeException: Connection terminated during handshake
The strange things are that it works, but I can't anyway render the widget with the error.
This is the code I used for fetching data:
Future<void> fetchAndSetWorkOrders([bool filterByUser = false]) async {
var url = Uri.parse(
'https://API_URL/wo?fields=id,code,description,statusCode,actionType,assignedTo&filter[wo][statusCode]=REQUEST');
try {
var response = await http.get(
url,
headers: {
"token": authToken,
},
);
var extractedData = json.decode(response.body) as Map<String, dynamic>;
final List<WorkOrder> loadedWorkOrders = [];
if (extractedData['data'] == null) {
return;
}
extractedData['data'].forEach(
(attribute) async {
var actionType_url = Uri.parse(attribute['relationships']
['actionType']['links']['related']);
var actionType_response = await http.get(
actionType_url,
headers: {
"token": authToken,
},
);
var actionTypeData = json.decode(actionType_response.body) as dynamic;
var actionType_code =
actionTypeData['data']['attributes']['code'];
print(actionType_code);
loadedWorkOrders.add(
WorkOrder(
id: attribute['id'],
code: attribute['attributes']['code'],
description: attribute['attributes']['description'],
statusCode: attribute['attributes']['statusCode'],
actionType: actionType_code,
),
);
},
);
This is an example of a JSON file I get from the API.
{
"data": [
{
"id": "17db1506f6d-3ca8",
"type": "wo",
"links": {
"self": "https://API_URL/wo/17db1506f6d-3ca8",
"workflow-transitions": "https://API_URL/wo/17db1506f6d-3ca8/workflow-transitions"
},
"attributes": {
"description": "test",
"code": "TEST",
"statusCode": "REQUEST"
},
"relationships": {
"actionType": {
"links": {
"self": "https://API_URL/wo/17db1506f6d-3ca8/relationships/actionType",
"related": "https://API_URL/wo/17db1506f6d-3ca8/actionType"
}
},
"assignedTo": {
"links": {
"self": "https://API_URL/wo/17db1506f6d-3ca8/relationships/assignedTo",
"related": "https://API_URL/wo/17db1506f6d-3ca8/assignedTo"
}
}
}
},
]
}
I hope that someone can help me to solve this problem.