`GW2v2Trait.Fact` can be "empty"

[Northburns]

Describe the bug

When fetching Trait 2330 "Resplendent Weaponry", deserialization fails with message "Disambiguator property not found" on the bits.

There is a fact with nothing but icon property. This is not documented behaviour in API docs (the trait in wiki for reference), and is likely a bug in the API itself.

To Reproduce

Trait 2330: https://api.guildwars2.com/v2/traits?ids=2330

Expected behavior

Since this unexpected behaviour in API is a show-stopper in using the library, I feel it should be handled. Maybe same solution as in #558 ?

Environment:

• api-generator version: 0.12.0
• Kotlin Version: 2.3.10
• Endpoint: https://api.guildwars2.com/v2/traits?ids=2330