Remove unused exceptions

backend/api/exceptions.py

@@ -2,16 +2,6 @@ from rest_framework import status
 from rest_framework.exceptions import APIException
 
 
-class FileParseException(APIException):
-    status_code = status.HTTP_400_BAD_REQUEST
-    default_detail = 'Invalid file format, line {}: {}'
-    default_code = 'invalid'
-
-    def __init__(self, line_num, line, code=None):
-        detail = self.default_detail.format(line_num, line)
-        super().__init__(detail, code)
-
-
 class LabelValidationError(APIException):
     status_code = status.HTTP_400_BAD_REQUEST
     default_detail = 'You cannot create a label with same name or shortcut key.'
@@ -20,8 +10,3 @@ class LabelValidationError(APIException):
 class AnnotationRelationValidationError(APIException):
     status_code = status.HTTP_400_BAD_REQUEST
     default_detail = 'You cannot create an annotation relation between the same annotation.'
-
-
-class RelationTypesValidationError(APIException):
-    status_code = status.HTTP_400_BAD_REQUEST
-    default_detail = 'You cannot create a relation type with same name or color.'