Custom Types property converter swallowing exceptions

[vinicius0026]

Hi there! First of all, thanks for your work on this library!

I had an issue with query.find and query.findFirst methods that took me a while to figure out and this ticket is intended to making that easier to debug.

If some exception is thrown on the setter of a Custom Types property converter, the exception is swallowed, making it hard to understand what is going on.

For example, say that we have a User entity with Custom Role type like this:

import 'package:flutter/material.dart';
import 'package:objectbox/objectbox.dart';

enum Role {
  user,
  admin,
}

@Entity()
class User {
  int id;
  String name;
  Role role;

  User({
    this.id = 0,
    required this.name,
    this.role = Role.user,
  });

  // custom type handling
  int get dbRole {
    return role.index;
  }
  set dbRole(int value) {
    // Exception thrown in the setter:
    throw ErrorDescription('swallowed error??');
  }
}

and we add some User records to the db (which will work fine).

Say that we then try to query the users like so:

// store is opened somewhere else
var box = store.box<User>();
var query = box.query().build();
var count = query.count();
var userIds = query.findIds();
var users = query.find();
var firstUser = query.findFirst();

In this case, the count and findIds queries work as expected, but the query.find() call returns an empty list and the query.findFirst() call returns null (even when count is > 0). This happens because the exception thrown in the set dbRole handler in the user class prevents User objects from being instantiated.

The problem is that this is hard to debug on a real use-case (not explicit exception thrown, but something else going wrong on the setter).

Looks like the exception is being swallowed somewhere in the runInTransaction call, but I was unable to find the exact spot.

Basic info:

• ObjectBox version: 1.1.1
• Flutter/Dart SDK:
  Flutter 2.2.2 • channel stable • https://github.com/flutter/flutter.git
  Framework • revision d79295af24 (9 weeks ago) • 2021-06-11 08:56:01 -0700
  Engine • revision 91c9fc8fe0
  Tools • Dart 2.13.3
• Null-safety enabled: yes
• Reproducibility: always
• OS: macOS Catalina 10.15.7
• Device/Emulator: iOS 14.4 iPhone 12 Pro Max Simulator

Steps to reproduce

See above, but to sum it up:

1. Have some exception thrown in a custom type converter setter.
2. Query the entity with find or findFirst

Expected behavior

The exception that is thrown in the setter should be visible to the developer so that it can be fixed appropriately.

Actual behavior

The exception is swallowed; query.find() returns empty list and findFirst() returns null even when query.count() is > 0.