Error properly if an invalid VM name is given

lib/vagrant/commands/status.rb

@@ -46,7 +46,7 @@ module Vagrant
         else
           # Try to get the vm based on the name. If the specified VM
           # doesn't exist, then error saying so
-          vm = env.vms[vm.to_sym]
+          vm = env.vms[vm.to_sym] || error_and_exit(:unknown_vm, :vm => vm)
         end
 
         show_single(vm)

templates/strings.yml

@@ -154,6 +154,8 @@
 :system_unspecified: |-
   A VM system type must be specified! This is done via the `config.vm.system`
   configuration value. Please read the documentation online for more information.
+:unknown_vm: |-
+  The specified VM could not be found: <%= vm %>
 :virtualbox_import_failure: |-
   The VM import failed! Try running `VBoxManage import` on the box file
   manually for more verbose error output.