core: don't delete data dir if no data dir [GH-4017]

CHANGELOG.md

@@ -6,6 +6,7 @@ IMPROVEMENTS:
 
 BUG FIXES:
 
+  - commands/package: base package won't crash with exception [GH-4017]
   - hosts/windows: RDP command works without crash. [GH-3962]
   - provisioners/puppet: Properly escape facter variables for PowerShell
       on Windows guests. [GH-3959]

lib/vagrant/machine.rb

@@ -301,6 +301,7 @@ module Vagrant
           @env.machine_index.delete(entry) if entry
         end
 
+        if @data_dir
           # Delete the entire data directory contents since all state
           # associated with the VM is now gone.
           @data_dir.children.each do |child|
@@ -311,6 +312,7 @@ module Vagrant
             end
           end
         end
+      end
 
       # Store the ID locally
       @id = value.nil? ? nil : value.to_s