Fixed issue with incomplete data returned from MailChimp
Fixed issue with incomplete data returned from MailChimp

Added defensive coding to MailChimpExportManager to prevent crashes and infinite loops where assumptions were made regarding the completeness of the MailChimp
export. There are times when not all members have all merge fields, this can cause infinite loops as well as crashes.

The changes I have made should mitigate this risk.

marmind/MailChimp.NET-APIv2,danesparza/MailChimp.NET