refactoring and checkpoint

lib/core/errors/exceptions.dart

@@ -27,3 +27,26 @@ class ServerExceptionWithMessage implements Exception {
   String toString() => 'ServerException: $message';
 }
 
+class UserNotFoundException implements Exception {
+  final String message;
+  UserNotFoundException([this.message = "User not found"]);
+
+  @override
+  String toString() => "UserNotFoundException: $message";
+}
+
+class ConflictException implements Exception {
+  final String message;
+  ConflictException([this.message = "Conflict"]);
+
+  @override
+  String toString() => "ConflictException: $message";
+}
+
+class UnauthorizedException implements Exception {
+  final String message;
+  UnauthorizedException([this.message = "Unauthorized"]);
+
+  @override
+  String toString() => "UnauthorizedException: $message";
+}