How do I go about troubleshooting autocompletion not working in Zsh?

I have a setup/cleanup script that successfully adds and removes:

```bash
# begin app completion
. <(app --completion)
# end app completion
```

I have also setup this alias in `~/.zshrc`: `alias lando='bin/app.js'`.

`app --completion` outputs:

```bash
### app completion - begin. generated by omelette.js ###
if type compdef &>/dev/null; then
_app_completion() {
compadd -- `app --compzsh --compgen "${CURRENT}" "${words[CURRENT-1]}" "${BUFFER}"`
}
compdef _app_completion app
elif type complete &>/dev/null; then
_app_completion() {
local cur prev nb_colon
_get_comp_words_by_ref -n : cur prev
nb_colon=$(grep -o ":" <<< "$COMP_LINE" | wc -l)

COMPREPLY=( $(compgen -W '$(app --compbash --compgen "$((COMP_CWORD - (nb_colon * 2)))" "$prev" "${COMP_LINE}")' -- "$cur") )

__ltrim_colon_completions "$cur"
}
complete -F _app_completion app
fi
### app completion - end ###
```

My `app.js` contains:

```
// Write your CLI template.
var completion = omelette('app ')

// This is your logic
completion.on('test', ({reply}) => { reply(['option1', 'option2']) });
completion.on('test2', ({reply}) => { reply(['option3', 'option4']) });

completion.init();
```

Now, I expect when that when I type `app` that I will see the options, but I do not. What are my next steps to troubleshooting? What command outputs the options that I hope to see? Is it possible that my JS is outputting garbage prematurely that breaks Zsh's autocompletion?