[in_app_purchase] [iOS] Host platform returned null value for non-null return value

[meowofficial]

Steps to reproduce

I got PlatformException(null-error, Host platform returned null value for non-null return value., null, null) in Sentry on production after calling SKPaymentQueueWrapper().storefront(). So far the issue occured only for one user.

package: in_app_purchase_storekit 0.3.14
device: iPhone 11
OS: iOS 17.4.1

Expected results

No error

Actual results

PlatformException(null-error, Host platform returned null value for non-null return value., null, null)

Code sample

Code sample

final storefront = await SKPaymentQueueWrapper().storefront();

Screenshots or Video

No response

Logs

No response

Flutter Doctor output

Doctor output

[✓] Flutter (Channel beta, 3.22.0-0.3.pre, on macOS 14.4.1 23E224 darwin-arm64, locale ru-RU)
    • Flutter version 3.22.0-0.3.pre on channel beta at /Users/admin/Application Support/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 87b652410d (3 weeks ago), 2024-04-23 21:41:18 -0500
    • Engine revision b4bfd45986
    • Dart version 3.4.0 (build 3.4.0-282.3.beta)
    • DevTools version 2.34.3

[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
    • Android SDK at /Users/admin/Library/Android/sdk
    • Platform android-34, build-tools 34.0.0
    • ANDROID_HOME = /Users/admin/Library/Android/sdk
    • Java binary at: /Applications/Android Studio.app/Contents/jbr/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 17.0.10+0-17.0.10b1087.21-11572160)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 15.3)
    • Xcode at /Applications/Xcode-15.3.0.app/Contents/Developer
    • Build 15E204a
    • CocoaPods version 1.15.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2023.3)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
      🔨 https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 17.0.10+0-17.0.10b1087.21-11572160)

[✓] IntelliJ IDEA Ultimate Edition (version 2024.1.1)
    • IntelliJ at /Applications/IntelliJ IDEA.app
    • Flutter plugin version 79.0.3
    • Dart plugin version 241.15989.9

[✓] VS Code (version 1.89.1)
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    • Flutter extension can be installed from:
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[✓] Connected device (5 available)
    • iPad (Evgeniy) (mobile)         • 00008020-001029592629402E            • ios            • iOS 17.1.2 21B101
    • iPhone 15 Pro (mobile)          • 7FE5FD9E-3748-405C-A6F2-F50CD2509BAD • ios            • com.apple.CoreSimulator.SimRuntime.iOS-17-4 (simulator)
    • macOS (desktop)                 • macos                                • darwin-arm64   • macOS 14.4.1 23E224 darwin-arm64
    • Mac Designed for iPad (desktop) • mac-designed-for-ipad                • darwin         • macOS 14.4.1 23E224 darwin-arm64
    • Chrome (web)                    • chrome                               • web-javascript • Google Chrome 124.0.6367.208

[✓] Network resources
    • All expected network resources are available.

• No issues found!

[stuartmorgan]

https://github.com/flutter/packages/blob/a99c7f5f5710f2bd63e873c5560093787baa9f51/packages/in_app_purchase/in_app_purchase_storekit/darwin/Classes/InAppPurchasePlugin.swift#L119-L122 isn't consistent with the Pigeon definition; both return lines can return nil, but the Pigeon definition says the return type is non-nullable. Either the Pigeon definition needs to change, or any nil value needs to set the out error (which is the reason the output shows as nullable on the native side per this comment).

Converting the generated code to Swift will help avoid this kind of thing since the non-nullable return types will actually become non-nullable since Swift uses throw rather than out errors.

[jmagman]

cc @LouiseHsu

[jmagman]

Assigning to @LouiseHsu as part of #119106