Ambiguous error message when dealing with immutable properties

[dnagler]

As we discussed on Slack, I ran into this stacktrace:

class kotlin.reflect.jvm.internal.KProperty1Impl cannot be cast to class kotlin.reflect.KMutableProperty1 (kotlin.reflect.jvm.internal.KProperty1Impl and kotlin.reflect.KMutableProperty1 are in unnamed module of loader 'app')
java.lang.ClassCastException: class kotlin.reflect.jvm.internal.KProperty1Impl cannot be cast to class kotlin.reflect.KMutableProperty1 (kotlin.reflect.jvm.internal.KProperty1Impl and kotlin.reflect.KMutableProperty1 are in unnamed module of loader 'app')
	at app.cash.tempest.internal.Binding.setDb(Codec.kt:188)

which didn't make it very obvious that the root cause was that I needed to change a val to a var.