First thing i'll say is that I know basically nothing about this, so a simple answer would be nice.
I installed a mod for Minecraft: Windows 10 and as I was trying to install the mod, I realized that there were multiple coding errors. So I went through, trying to fix what I could with memories of a coarse i did long ago. Eventually I came to an error that read: 'ModPE' is undefined. ModPE happened to be a common variable, used in stuff like ModPE.setItem very often. How can I fix this?