message: updated invocation name length requirements error handling
diff: @@ -156,8 +156,9 @@ class AlexaInteractionModel {
  let alexaModel = {};
  _.set(alexaModel, 'interactionModel.languageModel.invocationName', model.invocation);
  - if (alexaModel.interactionModel.languageModel.invocationName.length === 0) {
  - throw new Error(errorPrefix + 'Invocation cannot be empty');
  + if (alexaModel.interactionModel.languageModel.invocationName.length < 2 ||
  + alexaModel.interactionModel.language.invocationName.length > 50) {
  + throw new Error(errorPrefix + 'Invocation name must be between 2 and 50 characters.');
  }
  alexaModel.interactionModel.languageModel.types = [];
  