Kotlinx.serialization error

Example.kt

package io.github.dseelp.test

import kotlinx.serialization.KSerializer
import kotlinx.serialization.Serializable
import kotlinx.serialization.SerializationException
import kotlinx.serialization.builtins.serializer
import kotlinx.serialization.decodeFromString
import kotlinx.serialization.descriptors.SerialDescriptor
import kotlinx.serialization.descriptors.buildClassSerialDescriptor
import kotlinx.serialization.encoding.Decoder
import kotlinx.serialization.encoding.Encoder
import kotlinx.serialization.json.Json

fun main() {
    val json = Json {
        ignoreUnknownKeys = true
        coerceInputValues = true
        encodeDefaults = true
    }
    val inputText = """
        {
            "error": null,
            "value": {
                "user": {
                    "id": 123456789101112,
                    "name": "Test123",
                    "discriminator": 1234,
                    "avatarHash": "exampleTest",
                    "permissions": [
                    ]
                }
            }
        }
    """.trimIndent()
    println(json.decodeFromString<RestResult<UserResponse>>(inputText))
    println(json.decodeFromString<RestResult<Unit>>(inputText))
}

@Serializable
data class RestResponse<T>(val error: String? = null, val value: T? = null)


@Serializable(RestResultSerializer::class)
sealed class RestResult<T>

@Serializable
data class FailedRestResult<T>(val error: String) : RestResult<T>()

@Serializable
data class FineRestResult<T>(val value: T) : RestResult<T>()

class RestResultSerializer<T>(private val dataSerializer: KSerializer<T>): KSerializer<RestResult<T>> {
    override fun deserialize(decoder: Decoder): RestResult<T> {
        val response = decoder.decodeSerializableValue(RestResponse.serializer(dataSerializer))
        when {
            response.error == null && response.value == null -> throw SerializationException("")
            response.value != null && response.error != null -> throw SerializationException("")
            response.error != null -> return FailedRestResult(response.error!!)
            response.value != null -> return FineRestResult(response.value!!)
        }
        throw SerializationException()
    }

    override val descriptor: SerialDescriptor = buildClassSerialDescriptor("RestResult") {
        element("error", String.serializer().descriptor, isOptional = true)
        element("response", dataSerializer.descriptor, isOptional = true)
    }

    override fun serialize(encoder: Encoder, value: RestResult<T>) {
        val response = when (value) {
            is FailedRestResult -> RestResponse<T>(value.error, null)
            is FineRestResult -> RestResponse(null, value.value)
        }
        encoder.encodeSerializableValue(RestResponse.serializer(dataSerializer), response)
    }
}

@Serializable
data class User(
    val id: Long,
    val name: String,
    val discriminator: Int,
    val avatarHash: String?,
    val permissions: Array<Int>
) {
    override fun equals(other: Any?): Boolean {
        if (this === other) return true
        if (other !is User) return false

        if (id != other.id) return false
        return true
    }

    override fun hashCode(): Int {
        return id.hashCode()
    }
}

@Serializable
data class UserResponse(val user: io.github.dseelp.framecord.rest.data.objects.User)

output.txt

FineRestResult(value=UserResponse(user=User(id=123456789101112, name=Test123, discriminator=1234, avatarHash=exampleTest, permissions=[])))
Exception in thread "main" kotlinx.serialization.json.internal.JsonDecodingException: Unexpected JSON token at offset 43: Expected end of the object '}', but had ' ' instead
JSON input: .....: null,
    "value": {
        "user": {
            "id": 1.....
	at kotlinx.serialization.json.internal.JsonExceptionsKt.JsonDecodingException(JsonExceptions.kt:24)
	at kotlinx.serialization.json.internal.JsonExceptionsKt.JsonDecodingException(JsonExceptions.kt:32)
	at kotlinx.serialization.json.internal.AbstractJsonLexer.fail(AbstractJsonLexer.kt:514)
	at kotlinx.serialization.json.internal.AbstractJsonLexer.fail(AbstractJsonLexer.kt:219)
	at kotlinx.serialization.json.internal.AbstractJsonLexer.unexpectedToken(AbstractJsonLexer.kt:202)
	at kotlinx.serialization.json.internal.StringJsonLexer.consumeNextToken(StringJsonLexer.kt:70)
	at kotlinx.serialization.json.internal.StreamingJsonDecoder.endStructure(StreamingJsonDecoder.kt:59)
	at kotlinx.serialization.internal.ObjectSerializer.deserialize(ObjectSerializer.kt:43)
	at kotlinx.serialization.internal.UnitSerializer.deserialize(Primitives.kt)
	at kotlinx.serialization.internal.UnitSerializer.deserialize(Primitives.kt:79)
	at kotlinx.serialization.json.internal.PolymorphicKt.decodeSerializableValuePolymorphic(Polymorphic.kt:59)
	at kotlinx.serialization.json.internal.StreamingJsonDecoder.decodeSerializableValue(StreamingJsonDecoder.kt:35)
	at kotlinx.serialization.encoding.AbstractDecoder.decodeSerializableValue(AbstractDecoder.kt:43)
	at kotlinx.serialization.encoding.AbstractDecoder.decodeNullableSerializableElement(AbstractDecoder.kt:79)
	at io.github.dseelp.framecord.rest.client.jvm.RestResponse$$serializer.deserialize(Debug.kt:39)
	at io.github.dseelp.framecord.rest.client.jvm.RestResponse$$serializer.deserialize(Debug.kt:39)
	at kotlinx.serialization.json.internal.PolymorphicKt.decodeSerializableValuePolymorphic(Polymorphic.kt:59)
	at kotlinx.serialization.json.internal.StreamingJsonDecoder.decodeSerializableValue(StreamingJsonDecoder.kt:35)
	at io.github.dseelp.framecord.rest.client.jvm.RestResultSerializer.deserialize(Debug.kt:54)
	at io.github.dseelp.framecord.rest.client.jvm.RestResultSerializer.deserialize(Debug.kt:52)
	at kotlinx.serialization.json.internal.PolymorphicKt.decodeSerializableValuePolymorphic(Polymorphic.kt:59)
	at kotlinx.serialization.json.internal.StreamingJsonDecoder.decodeSerializableValue(StreamingJsonDecoder.kt:35)
	at kotlinx.serialization.json.Json.decodeFromString(Json.kt:100)
	at io.github.dseelp.framecord.rest.client.jvm.DebugKt.main(Debug.kt:104)
	at io.github.dseelp.framecord.rest.client.jvm.DebugKt.main(Debug.kt)

Process finished with exit code 1