Laravel custom artisan command error not showing line number

I created a custom command:

$> php artisan make:console TestCommand
Console command created successfully.

I edited it to make an error:

class TestCommand extends Command {
    ...
    public function handle()
    {
        echo $boo;
    }

And of course, it throws the error:

$> php artisan command:test

  [ErrorException]
  Undefined variable: boo

However, I don't get a line number!

It would help me track down problems with my command more easily if it could give me a line number, if not a full stack trace. What do I need to to do enable that?

via Chebli Mohamed