Can you explain the purpose and operation of ExceptionHandler when using coroutines in Kotlin?

In Kotlin, there is a special mechanism for handling exceptions in coroutines — CoroutineExceptionHandler. Its task is to catch unhandled exceptions that occur in coroutines and execute a specified handling code (for example, logging or showing a message to the user).

CoroutineExceptionHandler is a coroutine context element that can be added when launching a coroutine. It only triggers for exceptions that were not caught inside the coroutine itself (for example, in try-catch blocks).

Example of usage:

val handler = CoroutineExceptionHandler { _, exception ->
    println("Caught exception: ${exception.localizedMessage}")
}

GlobalScope.launch(handler) {
    throw RuntimeException("Error in coroutine")
}

Here, if an exception occurs in the coroutine, it will be caught and handled in handler. This is especially useful for centralized error handling in asynchronous code.