This was working differently in 2.79, tried tracking this down and it
seems this was wrong since the 2.8 beginning in {rB7907dfc40018}.
This would not only crash without an active scene camera, but would also
result in different tracks from different camera's constraints could not
be selected.
So select id depends on corresponding camera, remove the dependency on
scene camera completely.
Maniphest Tasks: T90651
Differential Revision: https://developer.blender.org/D12230