Palana 9dca07db30 libobs: Handle obs_scene_add failure
Previously a NULL item would cause a crash when reading transform info.
The crash can be reproduced by e.g. editing scenes.json so that two
scenes contain each other. Example scenes.json:

{
    "current_scene": "Scene",
    "sources": [
        {
            "flags": 0,
            "id": "scene",
            "mixers": 0,
            "name": "Scene",
            "settings": {
                "items": [
                    {
                        "align": 5,
                        "bounds": {
                            "x": 1440.0,
                            "y": 900.0
                        },
                        "bounds_align": 0,
                        "bounds_type": 2,
                        "name": "Scene 2",
                        "pos": {
                            "x": 0.0,
                            "y": 0.0
                        },
                        "rot": 0.0,
                        "scale": {
                            "x": 1.0,
                            "y": 1.0
                        },
                        "visible": true
                    }
                ]
            },
            "sync": 0,
            "volume": 1.0
        },
        {
            "flags": 0,
            "id": "scene",
            "mixers": 0,
            "name": "Scene 2",
            "settings": {
                "items": [
                    {
                        "align": 5,
                        "bounds": {
                            "x": 1.0,
                            "y": 1.0
                        },
                        "bounds_align": 0,
                        "bounds_type": 0,
                        "name": "Scene",
                        "pos": {
                            "x": 854.0,
                            "y": -520.0
                        },
                        "rot": 0.0,
                        "scale": {
                            "x": 1.75,
                            "y": 1.7562724351882935
                        },
                        "visible": true
                    }
                ]
            },
            "sync": 0,
            "volume": 1.0
        }
    ]
}
2015-02-17 13:41:49 +01:00
..
2015-02-11 13:10:53 -08:00
2014-02-12 08:04:50 -07:00