small. changes to simplify code + fix zero return error to warning

[drmowinckels]

Rather than throwing an error when zero records are found, throw a warning and return invisible NULL.
Makes is possible to run with apply's without erroring.

Also, small changes to the code for simplification:

• replace if statement in get events for checking event_status to match.arg
• change so that httr:GET path argument is used to collate api url and api_method, rather than pasting before.

One test is still failing, but I dont really understand vcr, so I'm not able to figure out what is going on.

[ledell]

Thanks @Athanasiamo! Tagging the associated issue here since it has not been tagged already: #89

I see you changed the name of the api_url arg to api_method since we only store the partial URL now (is that right? or maybe there's a different reason). We store something like "rladies-nashville/events" in that variable.

Would the technical term for that be "API endpoint" or "API path" (e.g. api_endpoint, api_path)? I don't know if "endpoint" can refer to the whole URL and/or just the suffix. I think that (HTTP) "method" would refer to the type of API interaction (GET, POST, DELETE), so I wonder if it makes sense to call api_method something slightly different.

cc @maelle

[drmowinckels]

@ledell , @maelle and I have also discussed the renaming of api_method since its not what you think it is by its name.
We decided the PR was already too large and that we wanted to do this in a separate step, to make it a little cleaner. I think I like the term api_path but dont know what would be the most intuitive.

[ledell]

@Athanasiamo I think api_path makes sense!