How to Resolve the "Error: Class kotlin.reflect.jvm.internal.FunctionCaller$FieldSetter" in Kotlin

What does the error 'Class kotlin.reflect.jvm.internal.FunctionCaller$FieldSetter' mean and how can I fix it?

class Example {
    var property: String = ""
}

fun main() {
    val example = Example()
    val setter = example::property
    setter.set("New Value") // Example of using reflection
}

The error 'Class kotlin.reflect.jvm.internal.FunctionCaller$FieldSetter' typically appears in Kotlin applications when there is an attempt to access or manipulate properties using reflection. This issue often arises when the reflection API is incorrectly employed or when incompatible types are involved.

import kotlin.reflect.KMutableProperty

fun main() {
    class Test(val name: String) {
        var age: Int = 30
    }
    val test = Test("John")
    val property: KMutableProperty<Int> = Test::age
    property.setter.call(test, 35) // Correct way to set property using reflection
    println(test.age) // Output: 35

Causes

• Inconsistent type usage in reflection.
• Accessing private fields without proper permissions.
• Incorrect initialization of properties before reflection access.

Solutions

• Ensure properties are initialized properly before use.
• Check for type compatibility when using reflection.
• Review visibility modifiers to allow access if needed.

Mistake: Trying to access a non-mutable property via reflection.

Solution: Ensure that the property you are trying to set is defined as mutable (i.e., using `var`).

Mistake: Forgetting to import the necessary reflection classes.

Solution: Always import the correct reflection libraries required for your functionality.