fix(data): revert throwError usages with factory for RxJS 6 compatibility

Closes #3702

Author: markostanimirovic

modules/data/src/dataservices/default-data.service.ts

@@ -168,7 +168,7 @@ export class DefaultDataService<T> implements EntityCollectionDataService<T> {
       }
       default: {
         const error = new Error('Unimplemented HTTP method, ' + method);
-        result$ = throwError(() => error);
+        result$ = throwError(error);
       }
     }
     if (this.timeout) {
@@ -184,7 +184,7 @@ export class DefaultDataService<T> implements EntityCollectionDataService<T> {
         return ok;
       }
       const error = new DataServiceError(err, reqData);
-      return throwError(() => error);
+      return throwError(error);
     };
   }
 

modules/data/src/dataservices/entity-cache-data.service.ts

@@ -79,7 +79,7 @@ export class EntityCacheDataService {
   protected handleError(reqData: RequestData) {
     return (err: any) => {
       const error = new DataServiceError(err, reqData);
-      return throwError(() => error);
+      return throwError(error);
     };
   }
 

modules/data/src/dispatchers/entity-cache-dispatcher.ts

@@ -206,14 +206,13 @@ export class EntityCacheDispatcher {
       mergeMap((act) => {
         return act.type === EntityCacheAction.SAVE_ENTITIES_CANCEL
           ? throwError(
-              () =>
-                new PersistanceCanceled(
-                  (act as SaveEntitiesCancel).payload.reason
-                )
+              new PersistanceCanceled(
+                (act as SaveEntitiesCancel).payload.reason
+              )
             )
           : act.type === EntityCacheAction.SAVE_ENTITIES_SUCCESS
           ? of((act as SaveEntitiesSuccess).payload.changeSet)
-          : throwError(() => (act as SaveEntitiesError).payload);
+          : throwError((act as SaveEntitiesError).payload);
       })
     );
   }

modules/data/src/dispatchers/entity-dispatcher-base.ts

@@ -590,10 +590,10 @@ export class EntityDispatcherBase<T> implements EntityDispatcher<T> {
       mergeMap((act) => {
         const { entityOp } = act.payload;
         return entityOp === EntityOp.CANCEL_PERSIST
-          ? throwError(() => new PersistanceCanceled(act.payload.data))
+          ? throwError(new PersistanceCanceled(act.payload.data))
           : entityOp.endsWith(OP_SUCCESS)
           ? of(act.payload.data as D)
-          : throwError(() => act.payload.data.error);
+          : throwError(act.payload.data.error);
       })
     );
   }