feat(@angular-devkit/schematics-cli): show error stacks instead of message

Otherwise its impossible to debug.

Author: hansl

packages/angular_devkit/schematics_cli/bin/schematics.ts

@@ -260,7 +260,7 @@ workflow.execute({
     } else if (debug) {
       logger.fatal('An error occured:\n' + err.stack);
     } else {
-      logger.fatal(err.message);
+      logger.fatal(err.stack || err.message);
     }
 
     process.exit(1);