fix: prevent iOS crash when rootViewController is nil during plugin registration

[Barba2k2]

Summary

• Fixed crash on iOS where rootViewController was force-unwrapped during plugin registration when it was still nil
• Changed viewController from a static stored property to a computed property that safely retrieves the root view controller
• Uses UIWindowScene for modern iOS with fallback for older versions

Problem

The app crashed with "force unwrapped a nil value" at line 64 of SwiftFlutterBarcodeScannerPlugin.swift during plugin registration because rootViewController is not yet available at that point in the app lifecycle.

Solution

Changed the static viewController property to a computed property that lazily and safely fetches the root view controller when actually needed (not during registration).

public static var viewController: UIViewController? {
    if let windowScene = UIApplication.shared.connectedScenes.first as? UIWindowScene,
       let rootVC = windowScene.windows.first?.rootViewController {
        return rootVC
    }
    return UIApplication.shared.delegate?.window??.rootViewController
}

[sonarqubecloud]

Quality Gate passed

Issues
6 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud