If you dig a big hole, don't fence it off, or mark it, and someone falls in it, then you are liable. How is leaving a firearm in plain view in an unlocked vehicle, or on a counter-top, less negligent? The goof who left his pocket pistol on a sofa in IKEA after it fell out of his pocket (a kid coon-fingered and fired it), at least was unaware of where his pistol was.
Rights and responsibility are a package deal, and if we accept leaving loaded guns unsecured as an acceptable standard, the people who are neutral about guns will support the gun banners who want to disarm us.
A, Indiana has a statute specifically granting immunity to victims of firearm theft, and B, The analogy is closer to a criminal seeing your hole, walking away, grabbing a passerby, and violently shoving them into the hole resulting in injury. The gun is inert. The kid didn't trip over it, he stole it and then pulled the trigger on someone. It's a willful act of agency. A gun possesses no inherent hazard until someone picks it up and decides to use it.