update stub methods to clarify behavior

src/repositories/UnoptimizedInMemoryRepository.ts

@@ -148,24 +148,30 @@ export class UnoptimizedInMemoryRepository implements GetterSetterRepository {
     }
   }
 
-
-  public async removeEta(shuttleId: string, stopId: string): Promise<void> {
+  removeSystemIfExists(systemId: string): Promise<ISystem | null> {
+    return Promise.resolve(null);
   }
 
-  public async removeOrderedStop(stopId: string, routeId: string): Promise<void> {
+  removeRouteIfExists(routeId: string): Promise<IRoute | null> {
+    return Promise.resolve(null);
   }
 
-  public async removeRoute(routeId: string): Promise<void> {
+  removeShuttleIfExists(shuttleId: string): Promise<IShuttle | null> {
+    return Promise.resolve(null);
   }
 
-  public async removeShuttle(shuttleId: string): Promise<void> {
+  removeStopIfExists(stopId: string): Promise<IStop | null> {
+    return Promise.resolve(null);
   }
 
-  public async removeStop(stopId: string): Promise<void> {
+  removeOrderedStopIfExists(stopId: string, routeId: string): Promise<IOrderedStop | null> {
+    return Promise.resolve(null);
   }
 
-  public async removeSystem(systemId: string): Promise<void> {
+  removeEtaIfExists(shuttleId: string, stopId: string): Promise<IEta | null> {
+    return Promise.resolve(null);
   }
+
   public async clearSystemData() {
     this.systems = [];
   }
@@ -189,4 +195,5 @@ export class UnoptimizedInMemoryRepository implements GetterSetterRepository {
   public async clearStopData(): Promise<void> {
     this.stops = [];
   }
+
 }