Error Código.gs:2 Cannot read property 'parameter' of undefined

[GATOS PROTECTORA]

hello, im trying to include a search google drive folder into my google sites using this GAS code but every time I try to execute this code i get the following error:

TypeError: Cannot read property 'parameter' of undefined

doGet

@ Código.gs:2

This is the code i'm using:

I do change the File Id section with the id of my google drive but i still get that error

Also i don't know what to change in the "fullText contains" section

I'm using the code provided by thop7777 from this thread: https://stackoverflow.com/questions/30109620/search-google-drive-folder-from-google-site-using-apps-script/37595910#37595910

Ty in advance!!

[Edward Ulle]

How are you trying to execute this code?  You need to put the link in a browser and include the parameter as shown in this link https://stackoverflow.com/questions/14736630/parameter-passing-to-webapp-on-dogete