checkpoint-duckdb: handle calling .list on async checkpointer (#3022)

libs/checkpoint-duckdb/langgraph/checkpoint/duckdb/aio.py

@@ -346,6 +346,18 @@ class AsyncDuckDBSaver(BaseDuckDBSaver):
         Yields:
             Iterator[CheckpointTuple]: An iterator of matching checkpoint tuples.
         """
+        try:
+            # check if we are in the main thread, only bg threads can block
+            # we don't check in other methods to avoid the overhead
+            if asyncio.get_running_loop() is self.loop:
+                raise asyncio.InvalidStateError(
+                    "Synchronous calls to AsyncDuckDBSaver are only allowed from a "
+                    "different thread. From the main thread, use the async interface. "
+                    "For example, use `checkpointer.alist(...)` or `await "
+                    "graph.ainvoke(...)`."
+                )
+        except RuntimeError:
+            pass
         aiter_ = self.alist(config, filter=filter, before=before, limit=limit)
         while True:
             try:

libs/checkpoint-postgres/langgraph/checkpoint/postgres/aio.py

@@ -385,7 +385,7 @@ class AsyncPostgresSaver(BasePostgresSaver):
             # we don't check in other methods to avoid the overhead
             if asyncio.get_running_loop() is self.loop:
                 raise asyncio.InvalidStateError(
-                    "Synchronous calls to AsyncSqliteSaver are only allowed from a "
+                    "Synchronous calls to AsyncPostgresSaver are only allowed from a "
                     "different thread. From the main thread, use the async interface. "
                     "For example, use `checkpointer.alist(...)` or `await "
                     "graph.ainvoke(...)`."