Steps to reproduce :

- import the project attached
- open the scene
- press play and Unity will crash

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Findings by Juha (in release/4.5/editor branch)

1. In user C# (gameinit.cs) the texture is null
2. When passed to Sprite_CUSTOM_INTERNAL_CALL_Create as ReadOnlyScriptingObjectOfType<Texture2D> it isn't null (IsNull()==false)
3. When passed onward to Sprite::Initialize as Texture2D, it's back to null again