I attempted to use the i2c.readerror() method after running a i2c.read(…) command that returned a null, but I get the following error:
[Device] ERROR: the index ‘readerror’ does not exist
The readerror() function is available in release30 and onwards (release 30 is currently in a semi-closed beta… if you haven’t given Hugo your MAC Address, you aren’t on release 30).
If you look at the “Availability” section on that page, it lists release 30 - the availability section of the API docs is a useful snippet to know about 
Availability: device (from release 30)
Is it possible to get updates like this automatically or even an email when a new version is released?
Moving forward, we’ll be using our Developer Newsletter to send out information about major releases. There is a signup link for the newsletter on the right side of the community site: