Handler Serde
## Description
The `duet.requests.handler` return value is broken currently due to serialization errors.

```
TypeError: You tried to deserialize an unsupported type. This can be caused by several reasons. Either you are actively writing Syft code and forgot to create one, or you are trying to deserialize an object which was serialized using a different version of Syft and the object you tried to deserialize is not supported in this version.
```

## How to Reproduce
Run: `duet.requests.handler`

## Expected Behavior
No error

## Additional Context
We will be refactoring this anyway.
diff --git a/src/syft/core/node/domain/service/request_handler_service.py b/src/syft/core/node/domain/service/request_handler_service.py
index 430177cf6..65036794a 100644
--- a/src/syft/core/node/domain/service/request_handler_service.py
+++ b/src/syft/core/node/domain/service/request_handler_service.py
@@ -117,6 +117,7 @@ class UpdateRequestHandlerMessage(ImmediateSyftMessageWithoutReply):
         return UpdateRequestHandlerMessage_PB
 
 
+@bind_protobuf
 class GetAllRequestHandlersMessage(ImmediateSyftMessageWithReply):
     def __init__(
         self, address: Address, reply_to: Address, msg_id: Optional[UID] = None
@@ -188,6 +189,7 @@ class GetAllRequestHandlersMessage(ImmediateSyftMessageWithReply):
         return GetAllRequestHandlersMessage_PB
 
 
+@bind_protobuf
 class GetAllRequestHandlersResponseMessage(ImmediateSyftMessageWithoutReply):
     def __init__(
         self,
diff --git a/src/syft/util.py b/src/syft/util.py
index 5a6a3ad18..2eec53cb2 100644
--- a/src/syft/util.py
+++ b/src/syft/util.py
@@ -34,7 +34,7 @@ def validate_type(_object: object, _type: type, optional: bool = False) -> Any:
 def validate_field(_object: object, _field: str) -> Any:
     object = getattr(_object, _field, None)
 
-    if object:
+    if object is not None:
         return object
 
     traceback_and_raise(f"Object {_object} has no {_field} field set.")
['src/syft/util.py', 'src/syft/core/node/domain/service/request_handler_service.py']