Resolve "Replace None with sentinel"

.../pages/presentationEditor/PresentationEditorPage.test.tsx

...t/src/pages/presentationEditor/PresentationEditorPage.tsx

client/src/pages/presentationEditor/styled.tsx

client/src/pages/views/OperatorViewPage.tsx

server/app/apis/alternatives.py

server/app/apis/answers.py

server/app/apis/auth.py

server/app/apis/competitions.py

server/app/apis/components.py

server/app/apis/media.py

server/app/apis/questions.py

server/app/apis/slides.py

server/app/apis/teams.py

server/app/apis/users.py

server/app/core/parsers.py

server/app/database/controller/edit.py