Error when getting jsmods_require on sent message

## Description of the problem
When a message is sent, a very long error can be seen in the console. No traceback is seen. The message is delivered.

## Code to reproduce
```py
#!/usr/bin/env python3
import fbchat
from fbchat import models

cookie_file = 'cookies.json'
with open(cookie_file, 'r') as fd:
cookies = json.load(fd)

client = fbchat.Client(email, password, session_cookies=cookies)

with open(cookie_file, 'w') as fd:
cookies = client.getSession()
json.dump(cookies, fd)

client.send(models.Message(text="test"), thread_id=owner) # owner = my UID
```

## Traceback
The error message is very long, to save you scrolling I've pastebinned it:
[https://pastebin.com/g5y46quv](https://pastebin.com/g5y46quv)

## Environment information
- Python version: Python 3.7.3
- `fbchat` version: 1.7.2

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