Fix T100879: Bake Action fails with "Nothing to Bake"

When applying the "Bake Action" operator in pose mode
it could throw an error saying "Nothing to Bake"
even though bones are selected

That is because the code was looking for a selected armature
But in Pose Mode, clicking into empty space to de-select would also
deselect the armature.
Then box selecting would not make the armature selected again

Reviewed by: Sybren A. Stüvel
Differential Revision: https://developer.blender.org/D16593

release/scripts/startup/bl_operators/anim.py

@@ -252,9 +252,14 @@ class NLA_OT_bake(Operator):
         do_pose = 'POSE' in self.bake_types
         do_object = 'OBJECT' in self.bake_types
 
-        objects = context.selected_editable_objects
-        if do_pose and not do_object:
-            objects = [obj for obj in objects if obj.pose is not None]
+        if do_pose and self.only_selected:
+            pose_bones = context.selected_pose_bones or []
+            armatures = {pose_bone.id_data for pose_bone in pose_bones}
+            objects = list(armatures)
+        else:
+            objects = context.selected_editable_objects
+            if do_pose and not do_object:
+                objects = [obj for obj in objects if obj.pose is not None]
 
         object_action_pairs = (
             [(obj, getattr(obj.animation_data, "action", None)) for obj in objects]