in src/com.jetbrains.youtrack.sdPlugin/libs/js/action.js [67:74]
onWillAppear(fn) {
if (!fn) {
console.error('A callback function for the willAppear event is required for onWillAppear.');
}
this.on(`${this.UUID}.${Events.willAppear}`, (jsn) => fn(jsn));
return this;
}