do not require ds100 codes in API responses

these are not present when other hafas backends than the DB one were
used for the trip's checkin.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/onboard/zugportal.rs b/src/onboard/zugportal.rs
index c649107..fe083ef 100644
--- a/src/onboard/zugportal.rs
+++ b/src/onboard/zugportal.rs
@@ -67,8 +67,8 @@ impl IsStation for Stop {
     self.arrival_time.as_ref().map(|t| &t.predicted)
   }
 
-  fn ds100(&self) -> &str {
-    "??"
+  fn ds100(&self) -> Option<&str> {
+    None
   }
 }