Description of problem:
Ordering a catalog item triggers at fatal error 

Version-Release number of selected component (if applicable):
5.6.2.1

How reproducible:
does not happen all the time

Steps to Reproduce:
1. order a catalog item
2. 
3.

Actual results:
the click on order for a catalog item does not open a dialog but results in an error invisible to the user.

[----] I, [2016-10-17T12:47:38.868068 #12193:1771a68]  INFO -- : Completed 200 OK in 77ms (Views: 1.6ms | ActiveRecord: 0.0ms)
[----] I, [2016-10-17T12:47:38.874937 #12174:177b8b0]  INFO -- :   Rendered layouts/_vertical_navbar.html.haml (262.0ms)
[----] I, [2016-10-17T12:47:38.913745 #12174:177b8b0]  INFO -- :   Rendered layouts/_x_form_buttons.html.haml (0.1ms)
[----] I, [2016-10-17T12:47:38.913926 #12174:177b8b0]  INFO -- :   Rendered layouts/_x_pagingcontrols.html.haml (3.2ms)
[----] I, [2016-10-17T12:47:38.915340 #12174:177b8b0]  INFO -- :   Rendered layouts/_dynatree.html.haml (0.2ms)
[----] I, [2016-10-17T12:47:38.915522 #12174:177b8b0]  INFO -- :   Rendered shared/_tree.html.haml (0.7ms)
[----] I, [2016-10-17T12:47:38.915693 #12174:177b8b0]  INFO -- :   Rendered shared/_explorer_tree.html.haml (1.0ms)
[----] I, [2016-10-17T12:47:38.915811 #12174:177b8b0]  INFO -- :   Rendered layouts/listnav/_explorer.html.haml (1.3ms)
[----] I, [2016-10-17T12:47:38.915929 #12174:177b8b0]  INFO -- :   Rendered layouts/_listnav.html.haml (1.7ms)
[----] I, [2016-10-17T12:47:38.916151 #12174:177b8b0]  INFO -- :   Rendered layouts/_content.html.haml (303.5ms)
[----] I, [2016-10-17T12:47:38.916717 #12174:177b8b0]  INFO -- :   Rendered layouts/_adv_search.html.haml (0.1ms)
[----] I, [2016-10-17T12:47:38.916884 #12174:177b8b0]  INFO -- :   Rendered layouts/_footer.html.haml (0.4ms)
[----] I, [2016-10-17T12:47:38.923532 #12174:177b8b0]  INFO -- : Completed 200 OK in 1833ms (Views: 341.0ms | ActiveRecord: 0.0ms)
[----] I, [2016-10-17T12:47:38.982236 #12156:1952ecc]  INFO -- : Started GET "/pictures/1r18.png" for 127.0.0.1 at 2016-10-17 12:47:38 +0200
[----] I, [2016-10-17T12:47:38.984065 #12156:1952ecc]  INFO -- : Processing by PictureController#show as */*
[----] I, [2016-10-17T12:47:38.984206 #12156:1952ecc]  INFO -- :   Parameters: {"basename"=>"1r18.png"}
[----] I, [2016-10-17T12:47:39.016184 #12156:1952ecc]  INFO -- :   Rendering text template
[----] I, [2016-10-17T12:47:39.016452 #12156:1952ecc]  INFO -- :   Rendered text template (0.0ms)
[----] I, [2016-10-17T12:47:39.020611 #12156:1952ecc]  INFO -- : Completed 200 OK in 36ms (Views: 1.4ms | ActiveRecord: 0.0ms)
[----] I, [2016-10-17T12:47:39.172715 #12164:177bd74]  INFO -- : Started GET "/pictures/1r12.png" for 127.0.0.1 at 2016-10-17 12:47:39 +0200
[----] I, [2016-10-17T12:47:39.174564 #12164:177bd74]  INFO -- : Processing by PictureController#show as */*
[----] I, [2016-10-17T12:47:39.174683 #12164:177bd74]  INFO -- :   Parameters: {"basename"=>"1r12.png"}
[----] I, [2016-10-17T12:47:39.179658 #12174:177be8c]  INFO -- : Started GET "/pictures/1r13.png" for 127.0.0.1 at 2016-10-17 12:47:39 +0200
[----] I, [2016-10-17T12:47:39.181255 #12174:177be8c]  INFO -- : Processing by PictureController#show as */*
[----] I, [2016-10-17T12:47:39.181390 #12174:177be8c]  INFO -- :   Parameters: {"basename"=>"1r13.png"}
[----] I, [2016-10-17T12:47:39.203386 #12164:177bd74]  INFO -- :   Rendering text template
[----] I, [2016-10-17T12:47:39.203557 #12164:177bd74]  INFO -- :   Rendered text template (0.0ms)
[----] I, [2016-10-17T12:47:39.206752 #12164:177bd74]  INFO -- : Completed 200 OK in 32ms (Views: 0.9ms | ActiveRecord: 0.0ms)
[----] I, [2016-10-17T12:47:39.213946 #12174:177be8c]  INFO -- :   Rendering text template
[----] I, [2016-10-17T12:47:39.214185 #12174:177be8c]  INFO -- :   Rendered text template (0.0ms)
[----] I, [2016-10-17T12:47:39.218531 #12174:177be8c]  INFO -- : Completed 200 OK in 37ms (Views: 1.4ms | ActiveRecord: 0.0ms)
[----] I, [2016-10-17T12:47:40.624539 #12184:176e91c]  INFO -- : Started POST "/dashboard/window_sizes?width=1920&height=926" for 127.0.0.1 at 2016-10-17 12:47:40 +0200
[----] I, [2016-10-17T12:47:40.625943 #12184:176e91c]  INFO -- : Processing by DashboardController#window_sizes as JS
[----] I, [2016-10-17T12:47:40.626119 #12184:176e91c]  INFO -- :   Parameters: {"width"=>"1920", "height"=>"926"}
[----] I, [2016-10-17T12:47:40.628265 #12184:176e91c]  INFO -- : Completed 200 OK in 2ms (ActiveRecord: 0.0ms)
[----] I, [2016-10-17T12:47:41.087317 #12202:175a674]  INFO -- : Started POST "/catalog/x_show/1r21" for 127.0.0.1 at 2016-10-17 12:47:41 +0200
[----] I, [2016-10-17T12:47:41.120878 #12202:175a674]  INFO -- : Processing by CatalogController#x_show as JS
[----] I, [2016-10-17T12:47:41.121028 #12202:175a674]  INFO -- :   Parameters: {"id"=>"1r21"}
[----] F, [2016-10-17T12:47:41.266253 #12202:175a674] FATAL -- : Error caught: [NoMethodError] undefined method `[]' for nil:NilClass
/var/www/miq/vmdb/app/presenters/tree_node_builder.rb:361:in `format_parent_id'
/var/www/miq/vmdb/app/presenters/tree_node_builder.rb:385:in `build_object_id'
/var/www/miq/vmdb/app/presenters/tree_node_builder.rb:44:in `build_id'
/var/www/miq/vmdb/app/presenters/tree_node_builder.rb:34:in `build_id'
/var/www/miq/vmdb/app/controllers/application_controller/explorer.rb:203:in `x_build_node_id'
/var/www/miq/vmdb/app/controllers/catalog_controller.rb:270:in `x_show'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_controller/metal/basic_implicit_render.rb:4:in `send_action'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/abstract_controller/base.rb:188:in `process_action'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/action_controller/metal/rendering.rb:30:in `process_action'
/opt/rh/cfme-gemset/gems/actionpack-5.0.0.1/lib/abstract_controller/callbacks.rb:20:in `block in process_action'
/opt/rh/cfme-gemset/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:126:in `call'
/opt/rh/cfme-gemset/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:126:in `call'
/opt/rh/cfme-gemset/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:506:in `block (2 levels) in compile'
/opt/rh/cfme-gemset/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:455:in `call'
/opt/rh/cfme-gemset/gems/activesupport-5.0.0.1/lib/active_support/callbacks.rb:455:in `call'


Expected results:
the catalog loads or an error displays

Additional info:
evm log displays warnings before the FATAL trace is raised : 

[----] I, [2016-10-17T12:47:10.257379 #12184:1771310]  INFO -- : <AutomationEngine> Updated namespace [Utility/ServiceDialogs/Methods/cert_create_contact  sIT/Utility/ServiceDialogs]
[----] I, [2016-10-17T12:47:10.265166 #12184:1771310]  INFO -- : <AutomationEngine> Invoking [inline] method [/sIT/Utility/ServiceDialogs/Methods/cert_create_contact] with inputs [{}]
[----] I, [2016-10-17T12:47:10.266133 #12184:1771310]  INFO -- : <AutomationEngine> <AEMethod [/sIT/Utility/ServiceDialogs/Methods/cert_create_contact]> Starting
[----] I, [2016-10-17T12:47:10.843388 #12184:63a0178]  INFO -- : <AutomationEngine> <AEMethod cert_create_contact> Ready to create new contact: {"first_name"=>nil, "last_name"=>nil, "email"=>nil}
[----] W, [2016-10-17T12:47:10.844008 #12184:63a0178]  WARN -- : <AutomationEngine> <AEMethod cert_create_contact> Tried to send empty value field - ABORT KWKWKW
[----] I, [2016-10-17T12:47:10.889323 #12184:1771310]  INFO -- : <AutomationEngine> <AEMethod [/sIT/Utility/ServiceDialogs/Methods/cert_create_contact]> Ending
[----] I, [2016-10-17T12:47:10.889548 #12184:1771310]  INFO -- : <AutomationEngine> Method exited with rc=MIQ_OK
[----] W, [2016-10-17T12:47:11.091213 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): Session object size of 310.7 KB exceeds threshold of 100 KB
[----] W, [2016-10-17T12:47:11.091613 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): _csrf_token <String> Size 44
[----] W, [2016-10-17T12:47:11.091947 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): breadcrumbs <Array> Size 80 Elements 1
[----] W, [2016-10-17T12:47:11.092115 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): browser <Hash> Size 119 Elements 5
[----] W, [2016-10-17T12:47:11.092254 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): changed <TrueClass> Size 3
[----] W, [2016-10-17T12:47:11.092611 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): css <Hash> Size 283 Elements 12
[----] W, [2016-10-17T12:47:11.092754 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): customer_name <String> Size 17
[----] W, [2016-10-17T12:47:11.142163 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): edit <Hash> Size 305541 Elements 10
[----] W, [2016-10-17T12:47:11.197981 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision):   current <Hash> Size 350 Elements 15
[----] W, [2016-10-17T12:47:11.198158 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision):   dialog_mode <NilClass> Size 3
[----] W, [2016-10-17T12:47:11.198296 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision):   explorer <TrueClass> Size 3
[----] W, [2016-10-17T12:47:11.198435 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision):   key <String> Size 26
[----] W, [2016-10-17T12:47:11.198577 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision):   new <Hash> Size 350 Elements 15
[----] W, [2016-10-17T12:47:11.198675 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision):   rec_id <Fixnum> Size 8
[----] W, [2016-10-17T12:47:11.198788 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision):   right_cell_text <String> Size 31
[----] W, [2016-10-17T12:47:11.198888 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision):   target_id <Fixnum> Size 8
[----] W, [2016-10-17T12:47:11.198976 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision):   target_kls <String> Size 15
[----] W, [2016-10-17T12:47:11.255839 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision):   wf <ResourceActionWorkflow> Size 304962
[----] W, [2016-10-17T12:47:11.261930 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): expkey <Symbol> Size 10
[----] W, [2016-10-17T12:47:11.262109 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): group <Fixnum> Size 8
[----] W, [2016-10-17T12:47:11.262280 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): host_url <String> Size 22
[----] W, [2016-10-17T12:47:11.262562 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): last_trans_time <Time> Size 88
[----] W, [2016-10-17T12:47:11.262758 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): lastaction <String> Size 4
[----] W, [2016-10-17T12:47:11.262926 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): layout <String> Size 8
[----] W, [2016-10-17T12:47:11.263149 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): paged_view_search_options <Hash> Size 246 Elements 12
[----] W, [2016-10-17T12:47:11.263293 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): panels <Hash> Size 52 Elements 3
[----] W, [2016-10-17T12:47:11.263891 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): sandboxes <ActiveSupport::HashWithIndifferentAccess> Size 2358 Elements 3
[----] W, [2016-10-17T12:47:11.264434 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): servicecatalog_sortcol <Fixnum> Size 8
[----] W, [2016-10-17T12:47:11.264614 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): servicecatalog_sortdir <String> Size 3
[----] W, [2016-10-17T12:47:11.265112 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): settings <Hash> Size 2535 Elements 6
[----] W, [2016-10-17T12:47:11.265539 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): sidebar <Hash> Size 21 Elements 1
[----] W, [2016-10-17T12:47:11.265661 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): svc_lastaction <String> Size 4
[----] W, [2016-10-17T12:47:11.265852 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): tab_bc <Hash> Size 4 Elements 0
[----] W, [2016-10-17T12:47:11.266001 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): tab_url <Hash> Size 180 Elements 2
[----] W, [2016-10-17T12:47:11.266137 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): user_TZO <Fixnum> Size 8
[----] W, [2016-10-17T12:47:11.266310 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): user_tz <String> Size 6
[----] W, [2016-10-17T12:47:11.266505 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): userid <String> Size 3
[----] W, [2016-10-17T12:47:11.266670 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): winH <String> Size 4
[----] W, [2016-10-17T12:47:11.266846 #12184:1771310]  WARN -- : MIQ(catalog_controller-svc_catalog_provision): winW <String> Size 4
[----] I, [2016-10-17T12:47:13.376047 #10229:12fd98c]  INFO -- : MIQ(MiqServer#populate_queue_messages) Fetched 7 miq_queue rows for queue_name=vmware, wcount=2, priority=200