fix: fail fast when no valid schemas

jina/serve/executors/__init__.py

@@ -168,6 +168,10 @@ def get_function_with_schema(fn: Callable) -> T:
         else:
             request_schema = docs_annotation or DocumentArray[LegacyDocument]
             response_schema = return_annotation or DocumentArray[LegacyDocument]
+            from docarray import DocList
+            if not issubclass(request_schema, DocList) or not issubclass(response_schema, DocList):
+                faulty_schema = 'request_schema' if not issubclass(request_schema, DocList) else 'response_schema'
+                raise Exception(f'The {faulty_schema} schema for {fn.__name__}: {request_schema} is not a DocList. Please make sure that your endpoints used DocList for request and response schema')
 
         return _FunctionWithSchema(fn, request_schema, response_schema)
 

tests/integration/docarray_v2/test_v2.py

@@ -716,6 +716,23 @@ def foo(self, docs: DocList[ImageDoc], **kwargs) -> DocList[ImageDoc]:
             pass
 
 
+@pytest.mark.parametrize('ctxt_manager', ['deployment', 'flow'])
+def test_wrong_schemas(ctxt_manager):
+    class MyExec(Executor):
+        @requests
+        def foo(self, docs: TextDoc, **kwargs) -> DocList[TextDoc]:
+            pass
+
+    if ctxt_manager == 'flow':
+        ctxt_mgr = Flow().add(uses=MyExec)
+    else:
+        ctxt_mgr = Deployment(uses=MyExec)
+
+    with pytest.raises(RuntimeFailToStart):
+        with ctxt_mgr:
+            pass
+
+
 @pytest.mark.parametrize('protocol', ['grpc', 'http', 'websocket'])
 def test_flow_incompatible_bifurcation(protocol):
     class First(Executor):