Unify null session handling for SessionData and TempData

[dariatiurina]

Currently TempData and SupplyParameterFromSession have different handling of null session. We should unify them and have consistent behaviour across the board.

[dariatiurina]

Based on #66832 (comment)

[github-actions]

Triage Summary

Area: area-blazor (the issue involves SupplyParameterFromSession, a Blazor-specific API for session-backed component parameters, alongside TempData session handling)
Type: Task (consistency improvement to unify two existing null-session handling implementations)

Potential Duplicates

• None found

Generated by Triage Comment Reviewer for dotnet/aspnetcore for issue #67175 · sonnet46 380.9K · ◷