I am trying to save model class data in DB using Spring with Kotlin but I am getting exception I am learning Spring with Kotlin and I am getting below exceptions while saving data in the local Database My Rest Controller looks like below @RestController class MarketPlaceController(val service: MessageService) { @GetMapping("/homepage") fun getHomePage() = "NFTs Marketplace" @GetMapping("/errorpage") fun getErrorPage() = "This is error" private var NFTs = mutableListOf( Message(1, "Title #1", "Description #1"), Message(2, "Sneaky Vampire Syndicate", "Description #2"),...