providers/hyperv: better errors

plugins/providers/hyperv/action/import.rb

@@ -29,12 +29,7 @@ module VagrantPlugins
           }
 
           env[:ui].info "Importing a Hyper-V instance"
-          begin
-            server = env[:machine].provider.driver.execute('import_vm.ps1', options)
-          rescue Error::SubprocessError => e
-            env[:ui].info e.message
-            return
-          end
+          server = env[:machine].provider.driver.execute('import_vm.ps1', options)
           env[:ui].info "Successfully imported a VM with name   #{server['name']}"
           env[:machine].id = server["id"]
           @app.call(env)

plugins/providers/hyperv/driver.rb

@@ -2,6 +2,8 @@ require "json"
 
 require "vagrant/util/powershell"
 
+require_relative "plugin"
+
 module VagrantPlugins
   module HyperV
     class Driver
@@ -13,9 +15,15 @@ module VagrantPlugins
       end
 
       def execute(path, options)
-        execute_powershell(path, options) do |type, data|
+        r = execute_powershell(path, options) do |type, data|
           process_output(type, data)
         end
+        if r.exit_code != 0
+          raise Errors::PowerShellError,
+            script: path,
+            stderr: r.stderr
+        end
+
         if success?
           JSON.parse(json_output[:success].join) unless json_output[:success].empty?
         else

plugins/providers/hyperv/errors.rb

@@ -6,6 +6,10 @@ module VagrantPlugins
         error_namespace("vagrant_hyperv.errors")
       end
 
+      class PowerShellError < HyperVError
+        error_key(:powershell_error)
+      end
+
       class PowerShellRequired < HyperVError
         error_key(:powershell_required)
       end

templates/locales/providers_hyperv.yml

@@ -1,6 +1,16 @@
 en:
   vagrant_hyperv:
     errors:
+      powershell_error: |-
+        An error occurred while executing a PowerShell script. This error
+        is shown below. Please read the error message and see if this is
+        a configuration error with your system. If it is not, then please
+        report a bug.
+
+        Script: %{script}
+        Error:
+
+        %{stderr}
       powershell_required: |-
         The Vagrant Hyper-V provider requires PowerShell to be available.
         Please make sure "powershell.exe" is available on your PATH.