made use of first class citizen objects as json validator functions

backend-dart/lib/domain/repository/project_repository.dart

@@ -13,7 +13,7 @@ abstract class ProjectRepository {
   TaskEither<IError, Project> update(ProjectUpdate project);
 
   /// Deletes a project by its unique ID.
-  TaskEither<IError, void> delete(String id);
+  TaskEither<IError, Project> delete(String id);
 
   /// Finds all projects.
   TaskEither<IError, List<Project>> findAll();

backend-dart/lib/domain/repository/project_task_repository.dart

@@ -16,7 +16,7 @@ abstract class ProjectTaskRepository {
   TaskEither<IError, ProjectTask> update(ProjectTaskUpdate task);
 
   /// Deletes a project task by its unique ID.
-  TaskEither<IError, void> delete(String id);
+  TaskEither<IError, ProjectTask> delete(String id);
 
   /// Finds all project tasks.
   TaskEither<IError, List<ProjectTask>> findAll();

backend-dart/lib/domain/repository/time_entry_repository.dart

@@ -19,7 +19,7 @@ abstract class TimeEntryRepository {
   TaskEither<IError, TimeEntry> update(TimeEntryUpdate timeEntry);
 
   /// Deletes a time entry by its unique ID.
-  TaskEither<IError, void> delete(String id);
+  TaskEither<IError, TimeEntry> delete(String id);
 
   /// Finds all time entries.
   TaskEither<IError, List<TimeEntry>> findAll();

backend-dart/lib/domain/repository/user_repository.dart

@@ -11,7 +11,7 @@ abstract class UserRepository {
 
   TaskEither<IError, User> update(UserUpdate user);
 
-  TaskEither<IError, void> delete(String id);
+  TaskEither<IError, User> delete(String id);
 
   TaskEither<IError, List<User>> findAll();
 }