li2cpp error Value of type 'int' is too large to convert to ushort

This has to do with the memory allocated to the variables you are using. Somewhere in your program it is trying to convert an integer into a ushort. This is a problem because an integer (also known as int32) takes up way more memory than a ushort (also known as unsigned int16).

An integer can be anything from -2,147,483,648 to 2,147,483,647. Or 32 bytes.

An ushort can be anything from 0 to 65535. Or 16 unsigned bytes (all positive)

So within your program you have an integer that is bigger than 65535. And When you are trying to convert it into a integer your run out of memory. That is the error you are getting.

To fix it, ensure that you do not use any ushort values in your program.

*EDIT: That being said, it looks like there is a problem with your UnityEngine library. I would suggest updating your Unity to the newest one or downloading the EnityEngine namespace for your current one into your Unity folder and replacing the old one.