Bug: test_dayview.py fails 4 tests #236

test_dayview.py fails 4 tests with the following errors when run by itself.

Steps to reproduce:

1. pytest tests\test_dayview.py

Result:

FAILED tests/test_dayview.py::test_dayview_html - AttributeError: 'NoneType' object has no attribute 'id'
FAILED tests/test_dayview.py::test_dayview_html_with_multiday_event[2021-2-1-57 / 101] - AttributeError: 'NoneType' object has no attribute 'id'
FAILED tests/test_dayview.py::test_dayview_html_with_multiday_event[2021-2-2-1 / 101] - AttributeError: 'NoneType' object has no attribute 'id'
FAILED tests/test_dayview.py::test_dayview_html_with_multiday_event[2021-2-3-1 / 57] - AttributeError: 'NoneType' object has no attribute 'id'