Enrichment of nullable fields is broken after https://github.com/bkbnio/kompendium/pull/566

[zakmilda]

Describe the bug
When applying an enrichment to a nullable field kompendium throws an exception

Exception in thread "main" java.lang.IllegalStateException: Incorrect enrichment type for enrichment id: thingA

To Reproduce
Steps to reproduce the behavior:

1. Change String to String? in

   kompendium/playground/src/main/kotlin/io/bkbn/kompendium/playground/util/Models.kt

   Line 8 in c9eb45f

   val thingA: String,

2. Try to run the EnrichmentPlayground
3. You receive an error Exception in thread "main" java.lang.IllegalStateException: Incorrect enrichment type for enrichment id: thingA

Expected behavior
Nullable fields should be correctly handled

Screenshots