JavaScript Uncaught TypeError: Cannot read property 'style' of null

I extracted Project 3 of CS50 Web programming and applied the migrations using the code

python manage.py makemigrations mail
python manage.py migrate
python manage.py runserver 

I created an account and logged in to the mail client but when I try sending an email and checking the sent folder the sent folder is empty. The error is

Uncaught TypeError: Cannot read property 'style' of null
at load_mailbox (inbox.js:59)
at HTMLButtonElement.<anonymous> (inbox.js:6)

Line 59 reads

 document.querySelector('#email-view').style.display = 'none';

The same error is also caused by a number of other lines. I am using Python 3.9.5.

Should you change 'none' to 'block' so it no longer of type null?

Can someone please help me?