Address GitHub Copilot comments

Author: lbkulinski

src/main/java/com/cta4j/alert/routestatus/RouteStatusApi.java

@@ -62,6 +62,8 @@ default List<RouteStatus> findByType(ServiceType type) {
      * @return a {@link List} of {@link RouteStatus}es associated with the bus route IDs, or an empty {@link List} if
      * no route statuses are found for the bus route IDs
      * @throws NullPointerException if {@code routeIds} is {@code null} or contains {@code null} elements
+     * @throws IllegalArgumentException if any of the {@code routeIds} matches a train line code (e.g. {@code "Red"});
+     * use {@link #findByLines(Collection)} instead
      * @throws Cta4jRouteStatusException if the API returns an error response or the response cannot be parsed
      */
     List<RouteStatus> findByBusRouteIds(Collection<String> routeIds);
@@ -73,6 +75,8 @@ default List<RouteStatus> findByType(ServiceType type) {
      * @return a {@link List} of {@link RouteStatus}es associated with the bus route ID, or an empty {@link List} if
      * no route statuses are found for the bus route ID
      * @throws NullPointerException if {@code routeId} is {@code null}
+     * @throws IllegalArgumentException if {@code routeId} matches a train line code (e.g. {@code "Red"}); use
+     * {@link #findByLine(TrainLine)} instead
      * @throws Cta4jRouteStatusException if the API returns an error response or the response cannot be parsed
      */
     default List<RouteStatus> findByBusRouteId(String routeId) {

src/main/java/com/cta4j/alert/routestatus/internal/impl/RouteStatusApiImpl.java

@@ -40,7 +40,7 @@ public final class RouteStatusApiImpl implements RouteStatusApi {
     private final AlertApiConfig config;
 
     public RouteStatusApiImpl(AlertApiConfig config) {
-        this.config = config;
+        this.config = Objects.requireNonNull(config);
     }
 
     @Override