Reproduction steps:
1. Open the attached “BugRepro” project
2. Drag the “Assets/Player32x32.png“ sprite to the Scene View
3. When the Editor asks, save the animation file anywhere

Expected results: The animation file is saved
Actual results: Unity Editor crashes

Reproduced with: 2022.3.45f1, 2022.3.46f1, 6000.0.16f1, 6000.0.19f1, 2021.3.44f1
Not reproduced with: 2022.3.44f1, 6000.0.15f1, 2021.3.43f1

Reproduced on: Ubuntu 22.04
Not reproduced on: Windows 10

First lines of the stack trace:
#2 0x00561a7a1e963a in PPtr<RuntimeAnimatorController>::operator RuntimeAnimatorController*() const
#3 0x00561a7b21bccd in Animator::GetEffectiveAnimatorController()
#4 0x00561a7a3cb074 in AnimatorController_CUSTOM_GetEffectiveAnimatorController(void*)
#5 0x00000042a3c496 in (wrapper managed-to-native) UnityEditor.Animations.AnimatorController:GetEffectiveAnimatorController_Injected (intptr)
#6 0x00000042a3c373 in UnityEditor.Animations.AnimatorController:GetEffectiveAnimatorController (UnityEngine.Animator)