Adds validation and error handling to signup

src/main/kotlin/net/halfbinary/scavengerhuntapi/controller/SignupController.kt

@@ -3,6 +3,7 @@ package net.halfbinary.scavengerhuntapi.controller
 import net.halfbinary.scavengerhuntapi.model.converter.toDomain
 import net.halfbinary.scavengerhuntapi.model.request.HunterSignupRequest
 import net.halfbinary.scavengerhuntapi.service.SignupService
+import org.springframework.http.ResponseEntity
 import org.springframework.web.bind.annotation.PostMapping
 import org.springframework.web.bind.annotation.RequestBody
 import org.springframework.web.bind.annotation.RestController
@@ -10,7 +11,13 @@ import org.springframework.web.bind.annotation.RestController
 @RestController
 class SignupController(private val signupService: SignupService) {
     @PostMapping("/signup")
-    fun hunterSignup(@RequestBody body: HunterSignupRequest) {
-        signupService.createNewHunter(body.toDomain())
+    fun hunterSignup(@RequestBody body: HunterSignupRequest): ResponseEntity<Any> {
+        try {
+            signupService.createNewHunter(body.toDomain())
+            return ResponseEntity.ok().build()
+        } catch (e: RuntimeException) {
+            return ResponseEntity.badRequest().body(e.message)
+        }
+
     }
 }