How to fix compiler errors before i enter playmode!

I went inside the console and this is the error that is always there, i have no idea what to do, but if this help’s i’m learning to make a game off of the old Island demo which i had to update the files before i could open it and that even came up with error’s which popped up in a new window asking me to fix it, which i did and well im stuck here trying to test something, the only things i have added is Grass Texture which is fine, and a First Person Controller (Prefab) but none of these are/is the compiler error this is the error given in to the console

Assets/Scripts/UnderwaterEffects.js(23,46): BCE0022: Cannot convert ‘UnityEngine.GameObject’ to ‘float’.

Please could someone help me, i’m new to unity and looking forward to the result’s

Double click on the error message. It will open the default script editor and highlight the line where this error occurs.

Looks like the type of a variable is incorrect at this line.