cli: avoid printing duplicate help, and print help on invalid command

.changeset/proud-eagles-grow.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli': patch
+---
+
+Fixed duplicate help output, and print help on invalid command

packages/cli/src/index.ts

@@ -27,18 +27,12 @@ const main = (argv: string[]) => {
 
   program.on('command:*', () => {
     console.log();
-    console.log(
-      chalk.red(`Invalid command: ${chalk.cyan(program.args.join(' '))}`),
-    );
-    console.log(chalk.red('See --help for a list of available commands.'));
+    console.log(chalk.red(`Invalid command: ${program.args.join(' ')}`));
     console.log();
+    program.outputHelp();
     process.exit(1);
   });
 
-  if (!process.argv.slice(2).length) {
-    program.outputHelp(chalk.yellow);
-  }
-
   program.parse(argv);
 };