[Flutter] Generator for flutter channel not working

[Nutlope]

Sanity checks

• [X] My issue relates to a specific CLI completion spec (e.g. git checkout is missing options in git completion spec). If your issue is more general, please create your issue here: withfig/fig
• [X] I have searched github.com/withfig/autocomplete/issues and there are no duplicates of my issue

What CLI tool does this relate to?

flutter channel

Which statement makes the most sense?

There is a bug with this completion spec

Issue Details

Flutter channel suggestions don't seem to be working.

[balogun14]

@Nutlope can you explain this a bit more