Error on collections with a null connection

[Ben Ritter]

Reproduce

new Mongo.Collection('mycollection', {connection: null});
Mongo.Collection.get('mycollection', {connection: "dummy val"}); // It only matters that connection is included.

Result

Uncaught TypeError: Cannot read property '_lastSessionId' of null

at line 16. That is, instance.options.connection is null.

[David Burles]

Thanks @BudgieInWA . I'll work on a fix shortly.