improved error handling and fixed meal plan api

cookbook/serializer.py

@@ -993,12 +993,6 @@ class MealPlanSerializer(SpacedModelSerializer, WritableNestedModelSerializer):
     def in_shopping(self, obj):
         return ShoppingListRecipe.objects.filter(mealplan=obj.id).exists()
 
-    def update(self, instance, validated_data):
-        if 'to_date' not in validated_data or validated_data['to_date'] is None:
-            validated_data['to_date'] = validated_data['from_date']
-
-        return super().update(instance, validated_data)
-
     def create(self, validated_data):
         validated_data['created_by'] = self.context['request'].user