Error when using AT command module

Hi all,

I'm using the AT module to send messages for interfacing to my GSM.

I've noticed I'm seeing a few errors pop out every so often when viewing the console:

Shutting down GSM Module
] "undefined1\r\n\r\nOK" <--- "1\r\n\r\nOK"
] "OK\r\n" <--- "\r\n"
Uncaught Error: Field or method "0" does not already exist, and can't create it on undefined
 at line 1 col 139
...)==f&&(b=c[f](b));"\n"==b[0]&&(b=b.substr(1));for(a=b.indexO...
                               ^
in function called from system
] "\r" <--- "\r"
] "\nNO" <--- "\nNO"
] "NORMA" <--- "RMA"
] "NORMAL P" <--- "L P"
] "NORMAL POWE" <--- "OWE"
] "NORMAL POWER D" <--- "R D"
] "NORMAL POWER DOWN" <--- "OWN"
] "NORMAL POWER DOWN \r\n" <--- " \r\n"
] "\r\n" <--- "\r\n"
Module Off

Obviously without viewing all of my code this is hard to track down but if someone could point my to where the AT command library is hitting this error I dont mind looking through my own code to pinpoint the issue. I'm assuming its something to do with registering listeners?