In an Android Kotlin app connected to a firestore backend,

I have the following data class:

import kotlinx.serialization.KSerializer
import kotlinx.serialization.Serializable
import kotlinx.serialization.descriptors.PrimitiveKind
import kotlinx.serialization.descriptors.PrimitiveSerialDescriptor
import kotlinx.serialization.descriptors.SerialDescriptor
import kotlinx.serialization.encoding.Decoder
import kotlinx.serialization.encoding.Encoder
import java.util.Date

@Serializable
data class Task(
    @Serializable(with = TaskCategorySerializer::class)
    val category: TaskCategory = TaskCategory.OTHER,
    @Serializable(with = Serializers.Companion.DateSerializer::class)
    val due_date: Date? = null,
)

object TaskCategorySerializer : KSerializer<TaskCategory> {
    override val descriptor: SerialDescriptor = PrimitiveSerialDescriptor("TaskCategory",
        PrimitiveKind.STRING)

    override fun serialize(encoder: Encoder, value: TaskCategory) {
        encoder.encodeString(value.name)
    }

    override fun deserialize(decoder: Decoder): TaskCategory {
        return try {
            val value = decoder.decodeString()
            if (value.isEmpty()) TaskCategory.OTHER else TaskCategory.valueOf(value)
        } catch (e: RuntimeException) {
            TaskCategory.OTHER
        }
    }
}

And I am fetching the tasks using the following code:

fun fetchTasks(boatId: String) {
        listenerRegistration = db.collection(Firestore.COLLECTION_TASKS)
            .addSnapshotListener { snapshot, exception ->
                if (exception != null) {
                    return@addSnapshotListener
                }
                if (snapshot != null && !snapshot.isEmpty) {
                    val tasks = snapshot.documents.map { task ->
                        task.toObject(Task::class.java)!!
                    }
                    _tasks.value = tasks
                } else {
                    Log.d(TAG, "Current data: null")
                }
            }
    }

When the DB contains values which are missing from the TaskCategory enum I am getting the following error in the logcat:

java.lang.RuntimeException: Could not deserialize object. Could not find enum value of
TaskCategory for value “” (found in field ‘category’)

I was expecting the custom deserializer to catch that exception and return a default value.

I do not understand why the custom deserializer is not being used. Is there another way to define a custom deserializer for firestore?