Add exception handler

src/main/kotlin/top/fatweb/api/controller/ExceptionController.kt

@@ -0,0 +1,14 @@
+package top.fatweb.api.controller
+
+import jakarta.servlet.http.HttpServletRequest
+import org.springframework.web.bind.annotation.RequestMapping
+import org.springframework.web.bind.annotation.RestController
+
+@RestController
+@RequestMapping("/error")
+class ExceptionController {
+    @RequestMapping("/thrown")
+    fun thrown(request: HttpServletRequest) {
+        throw request.getAttribute("filter.error") as RuntimeException
+    }
+}