[Plugin: Simple Import Users] Error

Got this error also, upon importing a number of users (I don’t have any other details, unfortunately, as it was reported to me by another user). It seems that the users were imported successfully despite the error.

Catchable fatal error: Object of class WP_Error could not be converted to string in… path/to/formatting.php on line 2829

Worth noting that I just enabled a caching plugin. I will try to replicate with and without that plugin, since that was my only recent change to the site.

I also have a minor hack in place that I doubt has anything to do with this: http://wordpress.org/support/topic/strip-non-alphanumeric-characters-from-generated-usernames?replies=1