[MOB-4049] Fix on the header VM

[d4r1091]

MOB-4049

Context

App crashed on iOS < 16 when trying to dequeue NTPHeader cell with an empty identifier.

Approach

The root cause

NTPHeaderViewModel.isEnabled returned true on all iOS versions, causing the section to be added to the collection view even on iOS < 16 where NTPHeader is unavailable.

Solution

Modified NTPHeaderViewModel.isEnabled to return false on iOS < 16. This makes shouldShow evaluate to false, filtering the section out before dequeue is attempted. The header section is completely excluded on devices running iOS < 16.

Other

Before merging

Checklist

• I performed some relevant testing on a real device and/or simulator for both iPhone and iPad

[github-actions]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 1 🔵⚪⚪⚪⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Recommended focus areas for review Behavior Change On iOS < 16 the header is now completely disabled regardless of feature flags. Confirm this aligns with product requirements and that no dependent logic assumes the header exists on older iOS versions. var isEnabled: Bool { if #available(iOS 16.0, *) { return AISearchMVPExperiment.isEnabled } return false } Test Coverage Consider adding unit/UI tests to validate that isEnabled returns true only on iOS >= 16 when the experiment is enabled, and false otherwise, to prevent regressions. var isEnabled: Bool { if #available(iOS 16.0, *) { return AISearchMVPExperiment.isEnabled } return false }

[github-actions]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Add compile-time availability guard Guard the feature flag access behind a compile-time check to prevent referencing unavailable symbols on older SDKs. This avoids potential runtime or compile-time issues when building with deployment targets below iOS 16. firefox-ios/Client/Ecosia/UI/NTP/Header/NTPHeaderViewModel.swift [72-77] var isEnabled: Bool { +#if compiler(>=5.7) if #available(iOS 16.0, *) { return AISearchMVPExperiment.isEnabled } +#endif return false } Suggestion importance[1-10]: 4 __ Why: The existing code already uses a runtime availability check and likely compiles fine; adding a compiler version guard offers marginal additional safety. The 'existing_code' matches the new hunk lines, and the improved code reflects the suggested change accurately.	Low

[d4r1091]

Merging this myself given the availability circumstances.