refactor: switch around pv.post and op.done so setpoint is set before readback

Author: shihab-dls

src/fastcs/transports/epics/pva/_pv_handlers.py

@@ -47,16 +47,15 @@ async def put(self, pv: SharedPV, op: ServerOperation):
         cast_value = cast_from_p4p_value(self._attr_w, raw_value)
 
         tracer.log_event("PV put", topic=self._attr_w, pv=pv, value=cast_value)
-        try:
-            await self._attr_w.put(cast_value)
-            op.done()
-        except Exception as e:
-            op.done(error=e)
+
         if isinstance(self._attr_w.datatype, Enum):
             pv.post(cast_to_p4p_value(self._attr_w, cast_value))
         else:
             pv.post(value)
 
+        await self._attr_w.put(cast_value)
+        op.done()
+
 
 class CommandPvHandler:
     def __init__(self, command: CommandCallback):