Revert "simplified sync decorator"

This reverts commit 51f1d81.

ably/decorator/sync.py

@@ -21,16 +21,19 @@ def wrapper(*args, **kwargs):
             pass
         ably_eventloop: events = AblyEventLoop.current().loop
 
-        # Handle calls from ably_eventloop on the same loop, return awaitable
-        if caller_eventloop is not None and caller_eventloop == ably_eventloop:
-            return ably_eventloop.create_task(fn(*args, **kwargs))
-
-        # Handle calls from external eventloop, post them on ably_eventloop
-        future = asyncio.run_coroutine_threadsafe(fn(*args, **kwargs), ably_eventloop)
-        if caller_eventloop is not None and caller_eventloop.is_running():
-            return asyncio.wrap_future(future)
-
-        # If called from regular function, return blocking result
-        return future.result()
-
-    return wrapper
+        res = fn(*args, **kwargs)
+        if asyncio.iscoroutine(res):
+            # Handle calls from ably_eventloop on the same loop, return awaitable
+            if caller_eventloop is not None and caller_eventloop == ably_eventloop:
+                return ably_eventloop.create_task(res)
+
+            # Handle calls from external eventloop, post them on ably_eventloop
+            future = asyncio.run_coroutine_threadsafe(res, ably_eventloop)
+            if caller_eventloop is not None and caller_eventloop.is_running():
+                return asyncio.wrap_future(future)
+
+            # If called from regular function, return blocking result
+            return future.result()
+        return res
+
+    return wrapper