Docs: Explain why/when `.lines()` returns an error
Docs: Explain why/when `.lines()` returns an error

aidancully/rust,graydon/rust,GBGamer/rust,graydon/rust,graydon/rust,GBGamer/rust,graydon/rust,GBGamer/rust,aidancully/rust,GBGamer/rust,aidancully/rust,aidancully/rust,aidancully/rust,GBGamer/rust,aidancully/rust,graydon/rust,GBGamer/rust,GBGamer/rust,graydon/rust,GBGamer/rust