Return early if the location is unknown

modules/hosts/t480/dwm/dwmblocks/weather.nix

@@ -9,7 +9,11 @@
           runtimeInputs = with pkgs; [ curl ];
 
           text = ''
-            curl -s https://wttr.in/Caerleon?format=%t
+            out="$(curl -s https://wttr.in/Caerleon?format=%t)"
+
+            [[ "$out" == *"Unknown location"* ]] && exit 1
+
+            echo "$out"
           '';
         })
       ];