Android export not working because something in one of my scripts.

Hi,

I`ve been trying to test my unity game on an android device but it crashes on startup after installing the .apk
I`ve been able to track this bug down to a script, but I can`t figure out wat is wrong with it. Unfortunately I have no permission to upload this script.

Unity documentation says duck-typing is not supported? Maybe this would be the issue, but I can`t figure out what ducktyping is exactly. What is the exact difference between duck-typing and no duck-typing?