Agenda fails to load if cookies are disabled

[NGPixel]

Describe the issue

With cookies disabled, the agenda fails to load because it throws DOMException: Failed to read the 'localStorage' property from 'Window': Access is denied for this document.

localStorage should be tested before accessing it, as per https://developer.mozilla.org/en-US/docs/Web/API/Web_Storage_API/Using_the_Web_Storage_API#testing_for_availability

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