Just putting it out here if anyone runs into a similar problem in the future:

If you call the native functions GetPosition() or GetRotation() (which obtain world-space location and rotation respectively) on a SkeletalMeshComponent instance that doesn't have its mesh set (SkeletalMesh property == none), the engine will hard-crash without any useful log. Conclusion: don't be dumb like me and make sure your SkeletalMeshComponents are set up properly at all times, especially if it's in your pawn.