IOS setup_log_stream Panic Exception

[TibiToz]

Hi,

I set up the logger to be able to send logs to Dart. I used the basic example for it. It is working great on Android, but on IOS an exception occurs when the log_stream is instantiated ( or re-instantiated but I don't understand how it could be called 2 times if it is the case).

Physical device:
IOS 15.8.3
iPad Air 2 (Model A1566)

Here are the error logs and my logger init code.
Rust:

flutter_logger::flutter_logger_init!(LevelFilter::Info);

#[flutter_rust_bridge::frb(init)]
pub fn init_app() {
    flutter_rust_bridge::setup_default_user_utils();
}

Dart:

Future setupLogger() async {
  setupLogStream().listen((msg) {
      logger("${msg.logLevel} ${msg.lbl.padRight(8)}: ${msg.msg}");
  });
}


Future<void> main() async {
  await RustLib.init();
  await setupLogger();
}

Error:

[ERROR:flutter/runtime/dart_vm_initializer.cc(41)] Unhandled Exception: PanicException(called Result::unwrap() on an Err value: SetLoggerError(())Backtrace [{ fn: "std::backtrace::Backtrace::create" }, { fn: "flutter_rust_bridge::misc::panic_backtrace::PanicBacktrace::setup::{{closure}}" }, { fn: "std::panicking::rust_panic_with_hook" }, { fn: "std::panicking::begin_panic_handler::{{closure}}" }, { fn: "std::sys_common::backtrace::rust_end_short_backtrace" }, { fn: "_rust_begin_unwind" }, { fn: "core::panicking::panic_fmt" }, { fn: "core::result::unwrap_failed" }, { fn: "rust_lib_app::api::discovery::setup_log_stream" }, { fn: "rust_lib_app::frb_generated::wirecrate__api__discovery__setup_log_stream_impl::{{closure}}::{{closure}}::{{closure}}" }, { fn: "rust_lib_app::frb_generated::wire__crate__api__discovery__setup_log_stream_impl::{{closure}}::{{closure}}" }, { fn: "<flutter_rust_bridge::handler::implementation::executor::SimpleExecutor<EL,TP,AR> as flutter_rust_bridge::handler::executor::Executor>::execute_normal::{{closure}}::{{closure}}" }, { fn: "<core::panic::unwind_safe::AssertUnwindSafe as core::ops::function::FnOnce<()>>::call_once" }, { fn: "std::panicking::try::do_call" }, { fn: "rust_try" }, { fn: "std::panicking::try" }, { fn: "std::panic::catch_unwind" }, { fn: "flutter_rust_bridge::misc::panic_backtrace::PanicBacktrace::catch_unwind" }, { fn: "<flutter_rust_bridge::handler::implementation::executor::SimpleExecutor<EL,TP,AR> as flutter_rust_bridge::handler::executor::Executor>::execute_normal::{{closure}}" }, { fn: "::call_box" }, { fn: "threadpool::spawn_in_pool::{{closure}}" }, { fn: "std::sys_common::backtrace::rust_begin_short_backtrace" }, { fn: "std::thread::Builder::spawn_unchecked::{{closure}}::{{closure}}" }, { fn: "<core::panic::unwind_safe::AssertUnwindSafe as core::ops::function::FnOnce<()>>::call_once" }, { fn: "std::panicking::try::do_call" }, { fn: "__rust_try" }, { fn: "std::panicking::try" }, { fn: "std::thread::Builder::spawn_unchecked::{{closure}}" }, { fn: "core::ops::function::FnOnce::call_once{{vtable.shim}}" }, { fn: "std::sys::pal::unix::thread::Thread::new::thread_start" }])

#0 SimpleDecoder.decode (package:flutter_rust_bridge/src/codec/base.dart:35:9)

#1 SseCodec._decode (package:flutter_rust_bridge/src/codec/sse.dart:42:55)

#2 SseCodec.decodeObject (package:flutter_rust_bridge/src/codec/sse.dart:32:12)

#3 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:847:45)

#4 Future._propagateToListeners (dart:async/future_impl.dart:876:13)

#5 Future._completeWithValue (dart:async/future_impl.dart:652:5)

#6 Future._asyncCompleteWithValue. (dart:async/future_impl.dart:722:7)

#7 _microtaskLoop (dart:async/schedule_microtask.dart:40:21)

#8 _startMicrotaskLoop (dart:async/schedule_microtask.dart:49:5)

Doctor summary (to see all details, run flutter doctor -v):
[!] Flutter (Channel [user-branch], 3.22.0-3.0.pre, on macOS 14.6.1 23G93 darwin-arm64, locale en-CH)
    ! Flutter version 3.22.0-3.0.pre on channel [user-branch] at /Users/rd/Documents/Flutter/flutter
      Currently on an unknown channel. Run flutter channel to switch to an official channel.
      If that doesn't fix the issue, reinstall Flutter by following instructions at
      https://flutter.dev/docs/get-started/install.
[✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
[✓] Xcode - develop for iOS and macOS (Xcode 15.4)
[✗] Chrome - develop for the web (Cannot find Chrome executable at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome)
    ! Cannot find Chrome. Try setting CHROME_EXECUTABLE to a Chrome executable.
[✓] Android Studio (version 2022.3)
[✓] VS Code (version 1.78.2)
[✓] Connected device (3 available)
    ! Error: Browsing on the local area network for iPhone. Ensure the device is unlocked and attached with a cable or
      associated with the same local area network as this Mac.
      The device must be opted into Developer Mode to connect wirelessly. (code -27)
[✓] Network resources

[fzyzcjy]

setup_default_user_utils sets up the logger (see its source code for details), so if you setup your own logger, you will setup Rust system logger twice, and I guess that's the error

[TibiToz]

Yes that was the error, thank you.

If I'm using this logger init
flutter_logger::flutter_logger_init!(LevelFilter::Info);
Will the rust exceptions be logged ? Or should I manually log them ?

[fzyzcjy]

flutter_logger is not developed by me, thus I guess you can ask the author of the package - cc @MnlPhlp :)

[MnlPhlp]

If setting up the logger twice is the problem why would it be different on ios and android?
Disabling the log feature of flutter_rust_bridge should solve it I think.

[TibiToz]

If setting up the logger twice is the problem why would it be different on ios and android? Disabling the log feature of flutter_rust_bridge should solve it I think.

Yup, disabling IOS log feature in frb resolved the issue. Thanks for your help