Fix error when there are no Sessions

[LuigiR0jas]

Description

App crashes if there are no sessions or conference. This PR solves that.

How has this been tested?

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• Manual testing
• System tests
• Unit tests
• None

Checklist

• CI pipeline is passing
• My code follows the conventions of this project
• I have performed a self-review of my code
• I have commented on my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (if applicable)
• I have added seed data to the database (if applicable)

Release tasks

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