System notifications bug

[Secreto31126]

Describe the bug System notifications break the phone variable in post() handler.

To Reproduce Steps to reproduce the behavior:

1. Get a phone change system notification
2. See error:

Error Unknown: TypeError: Cannot read properties of undefined (reading '0')
    at Object.post (requests:74:37)
    at doPost (https:28:55)

Expected behavior Don't fail

Desktop (please complete the following information):

• Runtime GAS
• Library Version 0.8.2

Additional context The breaking request was the following:

{
   "object": "whatsapp_business_account",
   "entry": [
      {
         "id": "",
         "changes": [
            {
               "value": {
                  "messaging_product": "whatsapp",
                  "metadata": {
                     "display_phone_number": "bot",
                     "phone_number_id": "bot"
                  },
                  "messages": [
                     {
                        "from": "user-87",
                        "id": "wamid",
                        "timestamp": "1689861876",
                        "system": {
                           "body": "User A changed from user-87 to user-67",
                           "wa_id": "user-67",
                           "type": "user_changed_number"
                        },
                        "type": "system"
                     }
                  ]
               },
               "field": "messages"
            }
         ]
      }
   ]
}

[Secreto31126]

The following line fails because contacts is not defined:

const contact = value.contacts[0];

Weird. I will consider changing it to value.messages[0].from, that is, if it's always available. I will research more on it later.