Something in vSphere instances seems to have no hardware "config" so triggers the following stack trace when listing VMs for the compute resource:

Operation FAILED: undefined method `template' for nil:NilClass
/usr/share/foreman/app/services/fog_extensions/vsphere/mini_servers.rb:28:in `block in allvmsbyfolder'
/usr/share/foreman/app/services/fog_extensions/vsphere/mini_servers.rb:23:in `each'
/usr/share/foreman/app/services/fog_extensions/vsphere/mini_servers.rb:23:in `allvmsbyfolder'
/usr/share/foreman/app/services/fog_extensions/vsphere/mini_servers.rb:25:in `block in allvmsbyfolder'
/usr/share/foreman/app/services/fog_extensions/vsphere/mini_servers.rb:23:in `each'
/usr/share/foreman/app/services/fog_extensions/vsphere/mini_servers.rb:23:in `allvmsbyfolder'
/usr/share/foreman/app/services/fog_extensions/vsphere/mini_servers.rb:13:in `all'
/usr/share/foreman/app/controllers/compute_resources_vms_controller.rb:5:in `index'

(reported by satar on #theforeman)