As I know, line markers should be placed only on special psi elements, for example, on class name identifier. Placing the marker on the wrong element may lead to its disappearing while file editing.
I place line marker on the `uClass.uastAnchor?.sourcePsi` element. Am I doing right? In Java files, it works perfectly. But in Kotlin it is not stable. I found an example in kotlin sources (https://github.com/JetBrains/kotlin/blob/ba6da7c40a6cc502508faf6e04fa105b96bc7777/idea/idea-android/src/org/jetbrains/kotlin/android/KotlinAndroidLineMarkerProvider.kt#L56), it is without UAST, however, it references the same element.
I tried kotlin versions 31 and 41. I suppose, there is a problem with the AST comparison in kotlin (leaf elements do not match correctly after changes).