<issue_start><issue_comment>Title: remove: avoid "Cannot convert undefined or null to object" error
username_0: When trying to remove an unexisting doc by his id, this.get() return null. 

But Null is an object so "Parameter is not an object" error is not trigger, 

Then hasOwnProperty.call throw error "Cannot convert undefined or null to object" rather than throw expected error "Object is not a document stored in the collection"
<issue_comment>username_0: @techfort hmm do you want a PR with a unit test perhaps ?