Description of problem: Thorws an error while trying to access Cloud Intel/Timelines

F, [2018-02-22T15:58:30.049392 #2615] FATAL -- : Error caught: [ArgumentError] comparison of NilClass with String failed
/home/hkataria/dev/manageiq-ui-classic/app/presenters/tree_builder_timelines.rb:51:in `sort'
/home/hkataria/dev/manageiq-ui-classic/app/presenters/tree_builder_timelines.rb:51:in `x_get_tree_roots'
/home/hkataria/dev/manageiq-ui-classic/app/presenters/tree_builder.rb:240:in `x_get_tree_objects'
/home/hkataria/dev/manageiq-ui-classic/app/presenters/tree_builder.rb:207:in `x_build_tree'
/home/hkataria/dev/manageiq-ui-classic/app/presenters/tree_builder.rb:141:in `build_tree'
/home/hkataria/dev/manageiq-ui-classic/app/presenters/tree_builder.rb:24:in `initialize'
/home/hkataria/dev/manageiq-ui-classic/app/presenters/tree_builder_timelines.rb:34:in `initialize'
/home/hkataria/dev/manageiq-ui-classic/app/controllers/dashboard_controller.rb:782:in `new'
/home/hkataria/dev/manageiq-ui-classic/app/controllers/dashboard_controller.rb:782:in `build_timeline_listnav'
/home/hkataria/dev/manageiq-ui-classic/app/controllers/dashboard_controller.rb:581:in `timeline'
/home/hkatar


Version-Release number of selected component (if applicable):


How reproducible:


Steps to Reproduce:
1. Click on Timelines sub tab under Cloud Intel maintab
2.
3.

Actual results:


Expected results:


Additional info: