Is there a list of all warnings and errors that one can suppress in Kotlin? I often have a hard time finding them

Also to answer directly: https://github.com/JetBrains/kotlin/blob/master/compiler/frontend/src/org/jetbrains/kotlin/diagnostics/rendering/DefaultErrorMessages.java

In addition to Kotlin compiler warnings/errors, there are IntelliJ IDEA ones (such as "SameParameterValue") that can be suppressed in the same way. They can be differentiated by having mixed-case names.

...also for IDEA Inspections you get this for F1 (stating it's an inspection), and there's usually a built-in suppression with Alt+Enter/bulb icon