[Backend] — Test: `SeasonsService.findActive` returns null when no season window matches now

[Olowodarey]

Background

SeasonsService.findActive (src/seasons/seasons.service.ts) returns the
active season where starts_at <= now < ends_at. If no such season exists, the
QueryBuilder .getOne() returns null. The existing season tests do not verify
the no-active-season case — there may be a missing null check that throws an
unexpected error.

Goal

Add tests for the no-active-season case in src/seasons/seasons.service.spec.ts
(create if absent).

Requirements

1. No season at all: mock query returns null; assert findActive returns
   null (or throws NotFoundException — verify the current implementation
   and match it).

2. Season exists but window hasn't started: season with
   starts_at = future; mock returns null; assert null returned.

Acceptance criteria

• No crashes when no active season exists.
• Correct season returned when one matches.

[gloskull]

Hello, I have 4 years of experience delivering solutions for projects like this, covering backend, frontend, and smart contract development. After carefully reviewing your requirements, I have a clear understanding of the task and am confident in my ability to deliver a clean, efficient, and thoroughly tested solution on time. I prioritize code quality, maintainability, and industry best practices throughout the development process.
My PR will be submitted in under 10hours.