Allocations in the Unity Editor when using GetComponent.

If you call gameObject.GetComponent, and there is no Collider on that gameObject, null is returned, but you will also see a memory allocation in the Unity profiler.

Why?

The call is actually returning a "fake null" object, so that when you try and use it a custom error message is displayed. This custom error message causes the allocation.

This behaviour is disabled in a build, so you will only ever see it in the editor.