Missing Reference Exception: The variable FOO of BAR doesn't exist anymore.

I have a basic scene with a 2D Rigidbody sprite and a controller script.

When I run my scene, I get the titled error, which makes one think the object is not assigned to the script in the inspector; however, it IS in fact assigned and there is nothing else that it should be assigned to.

What would cause such a basic scene to throw this message incorrectly? I have tried reassigning the object, I have deleted the script and recreated it and then reassigned it. No matter what I’ve done, it still throws the message.

This error wasn’t showing up previously, and things worked as expected, but I can’t think of what might have changed to give me this problem.

I’m also getting this. If I print the field immediately before making the call, the console shows that it is not null. If I hit error pause, when I get the error, I can also see in the inspector that the value is assigned, and that the prefab exists.