fix: report history storage availability clearly

modules/services/event-history-service/src/main/java/com/lingniu/ingest/eventhistory/ApiExceptionHandler.java

@@ -8,7 +8,9 @@ import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.RestControllerAdvice;
 import org.springframework.web.method.annotation.MethodArgumentTypeMismatchException;
 import org.springframework.web.server.ResponseStatusException;
+import org.springframework.web.servlet.resource.NoResourceFoundException;
 
+import java.io.IOException;
 import java.time.OffsetDateTime;
 import java.time.ZoneId;
 import java.time.format.DateTimeParseException;
@@ -69,6 +71,18 @@ public final class ApiExceptionHandler {
         return error(HttpStatus.BAD_REQUEST, "invalid date/time parameter: " + ex.getParsedString(), request);
     }
 
+    @ExceptionHandler(NoResourceFoundException.class)
+    public ResponseEntity<ApiError> noResource(NoResourceFoundException ex,
+                                               HttpServletRequest request) {
+        return error(HttpStatus.NOT_FOUND, "resource not found: " + request.getRequestURI(), request);
+    }
+
+    @ExceptionHandler(IOException.class)
+    public ResponseEntity<ApiError> io(IOException ex,
+                                       HttpServletRequest request) {
+        return error(HttpStatus.SERVICE_UNAVAILABLE, safeMessage(ex, "history storage unavailable"), request);
+    }
+
     @ExceptionHandler(Exception.class)
     public ResponseEntity<ApiError> generic(Exception ex,
                                             HttpServletRequest request) {