fix: correct 'does not exists' in two model error messages

Subject-verb agreement: 'Model does not exists or is not an LLM model'
-> 'Model does not exist ...' in the tool and chat serializers.

Author: simpleqt

apps/chat/serializers/chat.py

@@ -185,7 +185,7 @@ def generate_prompt(self, instance: dict):
             model_type__in=SUPPORTED_MODEL_TYPES
         ).exists()
         if not model_exist:
-            raise Exception(_("Model does not exists or is not an LLM model"))
+            raise Exception(_("Model does not exist or is not an LLM model"))
 
         def process():
             model = get_model_instance_by_model_workspace_id(model_id=model_id, workspace_id=workspace_id,

apps/tools/serializers/tool.py

@@ -1640,7 +1640,7 @@ def generate_code(self):
             SUPPORTED_MODEL_TYPES = ["LLM"]
             model_exist = QuerySet(Model).filter(id=model_id, model_type__in=SUPPORTED_MODEL_TYPES).exists()
             if not model_exist:
-                raise Exception(_("Model does not exists or is not an LLM model"))
+                raise Exception(_("Model does not exist or is not an LLM model"))
 
             def process():
                 model = get_model_instance_by_model_workspace_id(