App ID: 8af68145-6577-4dec-a5c9-c503349f4708

Description

We are experiencing a hard crash (fml::KillProcess()) in production when using native_ iOS plugins that handle background execution by spawning a secondary, headless FlutterEngine (specifically, native_geofence).

When the app is already running and patched via Shorebird, and a native iOS plugin forcefully instantiates a new FlutterEngine (using createFlutterEngine), Shorebird's TryLoadFromPatch attempts to load the patch for this secondary engine. It encounters a fatal error during DartSnapshot::IsolateSnapshotFromSettings and kills the entire process.

** Expected Behavior: **
While we understand that native plugins probably shouldn't start a whole new engine for background tasks, Shorebird should ideally fail gracefully here rather than taking down the entire application. If the patch cannot be safely applied to a secondary raw engine, can Shorebird fallback to the base snapshot or log a non-fatal error instead of invoking fml::KillProcess()?

Stack Trace:

Plaintext
3 Flutter fml::KillProcess()
4 Flutter fml::LogMessage::~LogMessage()
6 Flutter flutter::TryLoadFromPatch (patch_cache.cc:148)
7 Flutter flutter::ResolveIsolateData (dart_snapshot.cc:223)
8 Flutter flutter::DartSnapshot::IsolateSnapshotFromSettings
9 Flutter flutter::Shell::InferVmInitDataFromSettings
10 Flutter flutter::Shell::Create
11 Flutter -[FlutterEngine createShell:libraryURI:initialRoute:]
12 Flutter -[FlutterEngine runWithEntrypoint:libraryURI:initialRoute:entrypointArgs:]
13 native_geofence LocationManagerDelegate.createFlutterEngine()
Environment:

Shorebird 1.6.80
Flutter 3.38.9

Steps To Reproduce

1. Deploy a patch on an app that has configured native_geofence
2. See the app crash when the new patch is downloaded