test: fix all compilation errors and achieve coverage

walkguide-backend/demo/src/main/java/com/walkguide/controller/PairingController.java

@@ -7,7 +7,6 @@ import com.walkguide.security.SecurityHelper;
 import com.walkguide.service.PairingService;
 import lombok.RequiredArgsConstructor;
 import org.springframework.http.ResponseEntity;
-import org.springframework.security.core.Authentication;
 import org.springframework.web.bind.annotation.*;
 
 @RestController
@@ -42,9 +41,9 @@ public class PairingController {
     }
 
     @GetMapping("/status")
-    public ResponseEntity<ApiResponse<PairingStatusResponse>> status(Authentication auth) {
+    public ResponseEntity<ApiResponse<PairingStatusResponse>> status() {
         Long userId = SecurityHelper.getCurrentUserId();
-        String role = auth.getAuthorities().iterator().next().getAuthority();
+        String role = SecurityHelper.getCurrentUserRole();
         return ResponseEntity.ok(ApiResponse.ok(
                 pairingService.getStatus(userId, role), "Status pairing"));
     }

walkguide-backend/demo/src/main/java/com/walkguide/exception/GlobalExceptionHandler.java

@@ -31,8 +31,8 @@ public class GlobalExceptionHandler {
 
     @ExceptionHandler(RuntimeException.class)
     public ResponseEntity<ApiResponse<Object>> handleRuntime(RuntimeException ex) {
-        return ResponseEntity.status(HttpStatus.UNAUTHORIZED)
-                .body(ApiResponse.error("AUTH_ERROR", ex.getMessage()));
+        return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR)
+                .body(ApiResponse.error("INTERNAL_ERROR", ex.getMessage()));
     }
 
     @ExceptionHandler(Exception.class)

walkguide-backend/demo/src/main/java/com/walkguide/security/SecurityHelper.java

@@ -24,4 +24,12 @@ public class SecurityHelper {
         Authentication auth = SecurityContextHolder.getContext().getAuthentication();
         return auth != null ? auth.getName() : null;
     }
+
+    public static String getCurrentUserRole() {
+        Authentication auth = SecurityContextHolder.getContext().getAuthentication();
+        if (auth != null && auth.getAuthorities() != null && !auth.getAuthorities().isEmpty()) {
+            return auth.getAuthorities().iterator().next().getAuthority();
+        }
+        return null;
+    }
 }