I'm not clear about the context in which the AUTOLOAD is getting called. The immediate cause of the error is that $this is not a reference to an object.

You might want to run your script under the debugger (perl -d...), and run the script up to the line number where the error occurs (c nnn). Then you can do a stack trace (T) and also look at the variables involved (x $this; x $val; and so on).

Most likely you will find that the call to an undefined sub which triggered AUTOLOAD wasn't intended to go to this particular AUTOLOAD routine.