message: legacy message
diff: @@ -41,7 +41,21 @@ async function legacyMain(autorestArgs: string[]): Promise<number> {
  // generate virtual config file
  const currentDirUri = CreateFolderUri(currentDirectory());
  const dataStore = new DataStore();
  - const config = await CreateConfiguration(currentDirUri, dataStore.GetReadThroughScope(new RealFileSystem()), autorestArgs);
  + let config: AutoRestConfigurationImpl = {};
  + try {
  + config = await CreateConfiguration(currentDirUri, dataStore.GetReadThroughScope(new RealFileSystem()), autorestArgs);
  + } catch (e) {
  + console.error("Error: You have provided legacy command line arguments (single-dash syntax) that seem broken.");
  + console.error("");
  + console.error(
  + "While AutoRest keeps on supporting the old CLI by converting it over to the new one internally, " +
  + "it does not have crazy logic determining *what* is wrong with arguments, should conversion fail. " +
  + "Please try fixing your arguments or consider moving to the new CLI. " +
  + "Visit https://github.com/Azure/autorest/blob/master/docs/user/cli.md for information about the new CLI.");
  + console.error("");
  + console.error("Internal error: " + e);
  + return 1;
  + }
  // autorest init
  if (autorestArgs[0] === "init") {
  