readLine() that can be replaced with readln() or readlnOrNull().
Using corresponding functions makes your code simpler.
The quick-fix replaces readLine()!! with readln() and readLine() with readlnOrNull().
Examples:
val x = readLine()!!
val y = readLine()?.length
After the quick-fix is applied:
val x = readln()
val y = readlnOrNull()?.length