Fix typo

[hugovk]

Ran into this exception at hugovk/pypistats#101, here's some wording fixes:

"instancce" -> "instance"

And reword to avoid for "a Align instance"

[thombashi]

Thank you for your pull request.

Probably it would be more desirable to converting None values to default values automatically instead of raise exceptions.
I will modify that behavior.

[thombashi]

Fixed at 6863c1b