Need test cases to cover error handling in batch_work_executor.py

The documentation in the ReferenceToken should be generated into a nice HTML page for devs to more easily understand the code.

Describe the bug
The Send, Receive and Camera screens use the modal mode of react-navigation. The use of a cross icon in the top right corner of the screen is more suitable than using a back arrow on the top left corner of the screen.

To Reproduce
Steps to reproduce the behavior:

1. Create a new wallet
2. Click on 'Send' or 'Receive'
3. See