Fix swiss public transport line field none (#133964)

* fix #133116

The line can theoretically be none, when no line info is available (lets say walking sections first?)

* fix line field

* add unit test with missing line field

homeassistant/components/swiss_public_transport/coordinator.py

@@ -113,7 +113,7 @@ class SwissPublicTransportDataUpdateCoordinator(
                 destination=self._opendata.to_name,
                 remaining_time=str(self.remaining_time(connections[i]["departure"])),
                 delay=connections[i]["delay"],
-                line=connections[i]["line"],
+                line=connections[i].get("line"),
             )
             for i in range(limit)
             if len(connections) > i and connections[i] is not None
@@ -134,7 +134,7 @@ class SwissPublicTransportDataUpdateCoordinator(
                 "train_number": connection["train_number"],
                 "transfers": connection["transfers"],
                 "delay": connection["delay"],
-                "line": connection["line"],
+                "line": connection.get("line"),
             }
             for connection in await self.fetch_connections(limit)
         ]

tests/components/swiss_public_transport/fixtures/connections.json

@@ -23,8 +23,7 @@
     "platform": 2,
     "transfers": 0,
     "duration": "10",
-    "delay": 0,
-    "line": "T10"
+    "delay": 0
   },
   {
     "departure": "2024-01-06T18:06:00+0100",