Check for existence of keys in delete routines

[tmns]

Hi all 👋

When calling delete_all_events and delete_temporary_bitop_keys with an empty keys object the following exception is thrown:

TypeError: object of type 'NoneType' has no len()

This was also pointed out in the repo of the previous version here: Doist/bitmapist#31

To prevent the error from being thrown I changed the if len(keys) > 0 check to just if keys, as this both checks if it exists and if its length is greater than 0 (an empty list is falsy).

What do you think about this as a solution?

[imankulov]

Hi @tmns. Thanks for the report. As it turns out, it's actually a bitmapist-server issue (reported in Doist/bitmapist-server#10). While the server-side fix is not ready yet, I think your patch makes much sense. Will merge it in 👍