Insert failed - persistent minimongo 2

I am using meteor-persistent-minimongo2 to store my data offline. Everything is working fine apart from an error that I am getting. Not able to figure out the real cause.

No message (1)
insert failed: getErrorObject — aldeed_collection2-core.js:489
doValidate — aldeed_collection2-core.js:471
(anonymous function) — aldeed_collection2-core.js:223
(anonymous function) — frozeman_persistent-minimongo2.js:2518
(anonymous function) — frozeman_persistent-minimongo2.js:477
(anonymous function) — meteor.js:1195

Please help in rectifying this error.

tagging the creator of the package: @jeffm and @frozeman