Raise proper class if invalid options given for docker network

plugins/providers/docker/action/network.rb

@@ -64,8 +64,7 @@ module VagrantPlugins
             elsif options[:type] == "dhcp"
               network_name = "vagrant_network"
             else
-              # TODO: Make this an error class
-              raise "Must specify a `subnet` or use `dhcp`"
+              raise Errors::NetworkInvalidOption, container: machine.name
             end
             container_id = machine.id
 

plugins/providers/docker/errors.rb

@@ -45,6 +45,10 @@ module VagrantPlugins
         error_key(:docker_provider_nfs_without_privileged)
       end
 
+      class NetworkInvalidOption < DockerError
+        error_key(:network_invalid_option)
+      end
+
       class PackageNotSupported < DockerError
         error_key(:package_not_supported)
       end

templates/locales/providers_docker.yml

@@ -197,6 +197,9 @@ en:
         is functional and properly configured.
 
         Host VM ID: %{id}
+      network_invalid_option: |-
+        Invalid option given for docker network for guest "%{container}". Must specify either
+        a `subnet` or use `type: "dhcp"`.
       package_not_supported: |-
         The "package" command is not supported with the Docker provider.
         If you'd like to commit or push your Docker container, please SSH